Handbook c7 metals and non metals by Agastya International Foundation

Agastya International Foundation

Metals and Non-Metals Handbook C7

â&#x20AC;&#x153;A scientist in his laboratory is not a mere technician: he is also a child confronting natural phenomena that impress him as though they were fairy tales.â&#x20AC;? -Marie Curie (1867-1934)

Handbook C7 Metals and Non-Metals OVERVIEW OF HANDBOOK ABL

CONCEPT

NO. OF ACTIVITIES 4

ABL1

How and why do we classify elements?

ABL2

Chemical properties of metals and non-metals

ABL 3

From where do we get metals?

PAGE NO. 4

ABLs WITH REFERENCE TO STANDARD SERIAL NUMBER 1 2 3

STANDARD 8, 9, 10 10 10

RELEVANT ABL ABL1 ABL2 ABL3

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TIME (min)

LIST OF FIGURES, CHARTS AND WORKSHEETS

S. No Figure 1 Figure 2 Chart 1 Chart 2 Chart 3 Chart 4 Chart 5 Chart 6 Worksheet 1 Worksheet 2 Worksheet 3 Worksheet 4 Worksheet 5 Worksheet 6

Name Activity series for Instructor reference Extraction of Copper by Electrolysis Houses Picture card Metal objects – flip chart (pot, wire, coins, tank) Activity series chart Electronic configuration chart Flip chart of metal objects 2 – School bus, switch, trumpet, bicycle) Flip chart – Rusted nail, old copper, blackened silver, Iron and steel vessel Student worksheet - Houses Word search activity sheet Student observation sheet – Physical properties Student observation sheet – reaction with water Student observation sheet – reaction with acid Application of alloys

Page No 36 42 5 8 15 30 33 44 5 5 8 21 23 44

Note to Instructor: All the figures in this handbook are for the Instructor’s reference only. The Charts need to be printed and shown to the learners during the course of the activity. Worksheets need to be printed out in advance for the students. The number of worksheets required is mentioned in the Material List.

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ABL 1 – HOW AND WHY DO WE CLASSIFY ELEMENTS Activity

Learning Objective 

1.1

Why do we classify elements? How do we classify elements?

   

1.2

How do we know if something is a metal or a nonmetal based on their physical properties?

 

Key Messages

Time (min)

Classifying materials/elements according to their properties helps us to see trends and patterns in their behaviour. It also gives us a better idea of their application in daily life Elements can be broadly classified into metals, non-metals and metalloids based on their properties We classify elements based on their physical and chemical properties The simplest way to describe a metal/non metal is by looking at its physical properties (which can be seen, heard etc. when the material is in its existing/native state) The physical properties of a metal are lustre, hardness, malleability, ductility, conductivity and sonority. Non-metals usually exist as gases or brittle solids. They are poor conductors of electricity and have lower melting and boiling points than those of metals. Total Time

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4 Time: 30 min

ABL 1.1 LEARNING OBJECTIVE –Why do we classify elements? How do we classify elements? Note to Instructor –1.1 a: This activity is a quick discussion where learners must understand the purpose of learning the properties of a material. 1.1 b: In this activity, you do not need to explain the chemistry behind rusting/corrosion. The learner only needs to understand that different materials have different properties and hence, they are classified into metals and non-metals based on some of these common properties.

ADVANCE PREPARATION Material List S. No. 1 2

Material Houses picture card – blow up A3 – Chart 1 Student worksheet – Worksheet 1

Required Quantity 1 per class

Word search activity sheet – Worksheet 2 (given at the end of the handbook)

1 per learner

Things to Do Print Worksheets 2 & 3 for each learner. These can be printed back to back to save paper. Safety Precautions Not Applicable

SESSION SESSION 1.1a Link to known information/previous activity Not Applicable Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Procedure Discuss the need to understand the different types of materials using the leading questions. Pick out different learners to respond to the question. Note to Instructor - Do not take too long with this activity, as it is only an introduction.

UNDERSTANDING THE ACTIVITY Leading Questions 1. What do you think would happen if I cooked in a vessel made of cardboard? 2. How do we decide what material to use when we decide to make or build something? 3. What would be the best kind of material for a digging tool? [Use the process discussed above to decide.] 4. What conclusion do you draw from these examples? Discussion and Explanation 1. The cardboard would catch fire and one will not be able to cook anything in it. 2. When we want to make something new, we first need to decide what the purpose of that thing will be. Once we decide the purpose, we can decide which material will be suitable for it to perform that duty. 3. The purpose of the digging tool is to be sharp, strong and durable when it cuts through the soil. So we will also need a material that is strong and durable and which can be made sharp. 4. In this manner, if we know the characteristics/properties of various materials/substances we can use our knowledge to help us make the right choices in daily life application of these materials.Putting this knowledge in order (classifying), based on these properties will make it easy for us to choose from them whenever necessary. SESSION 1.1b Link to known information/previous activity Now that we know why we need to classify materials, let us see how to choose a material for a specific purpose. How do we do the classification?

Procedure Tell the learners that they will now need to make a choice. They will be choosing material for the purpose of building a house. Show them the picture card of the two houses A and B (Chart 1). Tell them that they need to answer a few questions about these houses in five minutes after which they can share their answers. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

House picture cards – Chart 1 Give out the worksheets and give the learners five minutes to write down their choices. Discuss their answers. At the end of the discussion, askthe learners to do the metal and non-metal word search sheet (behind their previous worksheet) to make then familiar with the names of some common metals and nonmetals. Give them five minutes to try this after which they can continue it at home. Note to Instructor - This can become a take home activity if you are short of time.

UNDERSTANDING THE ACTIVITY Leading Questions (same questions on the worksheet) 1. You can see that house A and B are built of different materials. What material was used to build house A? 2. What material was used to build house B? 3. If you had to build a house next to the sea, which would you choose, House A or B? Why? 4. Write down at least three other materials that could be used for building a house or parts of a house. Discussion and Explanation 1. House A is built of tin/metal 2. House B is built out of wood 3. One should build House B – made of wood, near the ocean, as it will last longer. The large amounts of moisture in the air near the sea will cause the metal to rust/corrode/get damaged and break. 4. Cement, stones, bricks etc can be used to build a house. Now that we know the different types of materials that we could use to build a house and have seen the different cases when you would use one material or another, let’s look at the actual classification of these materials. Materials can be broadly classified into metals and non-metals based on their Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

properties. Each class has its own unique set of properties. Properties are the things that are special or unique about an object or material. We can use the properties of a metal or non-metal to describe what it is like. Some of these properties that can be observed in the material are called physical properties and the properties that give rise to a change in the chemical nature of the material are called chemical properties of the metal or non-metal. Some materials exist that show properties of both metals and non-metals in different conditions. These substances are called metalloids.

KEY MESSAGES: 

Classifying materials/elements according to their properties helps us to see trends and patterns in their behaviour.  It also gives us a better idea of their application in daily life  Elements can be broadly classified into metals, non-metals and metalloids based on their properties  We classify elements based on their physical and chemical properties

LEARNING CHECK: 1) Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the key messages chart. If you have time during the class, make up a small game or quiz or match the following as a learning check. This may have to be done as part of advance preparation. 2) Name three metals and three non-metals.

INTERESTING INFORMATION: The distinction between non-metals and metals is not always clear. The result is that a few borderline elements lacking a majority of either non-metallic or metallic properties are classified as metalloids and some elements classified as non-metals are instead sometimes classified as metalloids, or vice versa. For example, Selenium (Se), a non-metal, is sometimes classified instead as a metalloid, particularly in environmental chemistry; and Astatine (At), which is a metalloid and a halogen, is sometimes classified instead as a nonmetal.

Time: 30 min

ABL 1.2 Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

LEARNING OBJECTIVE – How do we know if something is a metal or a non-metal based on their physical properties? ADVANCE PREPARATION Material List Sl.No. 1

4 3

Material Metal object set – coins, spoon, metal nail/screw, paper clip, steel wool, metal bottle cap Non-metal objects set – paper, cotton, cloth, plastic spoon, sponge, chalk, strong glass piece etc. Metal object images – flip charts – Chart 2 Student observation sheet Worksheet 3 (metal and nonmetal table on same sheet)

Required Quantity 1 per group

1 per group

1 set per class 1 per group

Things to Do Make sure you make 6 sets of the metal and non-metal objects in separate bags and keep them ready for the groups. Safety Precautions Not Applicable

SESSION Link to known information/previous activity Now we know that materials are classified into metals and non-metals. We also know that a property is that thing which is special or unique about that object.Let us now try and see if we can find some of their physical properties. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

SESSION 1.2a Procedure Ask learners to form groups of six. Explain to them that each group will get a tray of metal objects and another tray of non-metal objects. Ask them to observe these carefully, touch them, feel the shape, does it feel or cold, rough or smooth, is it shiny or dull, can you describe it colour, drop the object on the floor and observe if it makes a sound. Ask them to write down their observations in the given table. Tell them that a few key words that they can use to describe the object are given at the top of the page. Tell them to repeat this process for both trays and fill in their observations in the respective tables. Ask them to each write down the observation for one object so that the activity is completed quickly. KEY WORDS: shiny, dull, rough, hard, smooth, makes a ringing sound, cold, warm, heavy, rigid, sharp, flexible, soft, light (Worksheet 3 â&#x20AC;&#x201C; for Instructor reference) Name of the object How the objects What the object The sound that the feels when I touch looks like object made when I it dropped it/ tapped it on the ground (learners can spell the sound if they like)

UNDERSTANDING THE ACTIVITY Leading Questions 1. Look at the two tables that you filled in. Did you notice any common property among the metals? 2. Did you notice any common properties among the non-metals? 3. Did any object have just one property? (Only one key word) Discussion and Explanation 1. Metals were all shiny, and mostly hard and heavy. Some of the metals showed different features. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

2. Most of the non-metals were dull and did not make much noise when they were dropped. Non-metals have varying features. Some are soft and some are hard. They can be heavy or light. 3. All objects had more than one property. That means that a material is classified as a metal or a nonmetal based on a list of properties and not just one property. We also notice that there are some common properties between certain metals and certain nonmetals. This is why we must use the entire list of properties to classify a given material.

SESSION 1.2b Note toInstructor â&#x20AC;&#x201C; this activity is to familiarize the learners with technical names for the physical properties of metals and non-metals Procedure Tell the learners that now that they know the general properties of metals and non-metals, you will now show them photos of different objects made from metal and non-metals. They will have to answer a few questions about each object. Show each picture from the flip chart (Chart 2) and ask leading question and discuss the property to which it is related. Move on to the next picture. Repeat this for all the pictures till each of the properties is covered.

Metal pot

barbed wire

coins

tank

(FLIP CHART)

UNDERSTANDING THE ACTIVITY Leading Questions 1. 2. 3. 4.

What are some properties of the metal that the pot is made of? Why are some of these properties useful to the function of the pot? What property of metal allows us to make this barbed wire from the metal? What other functions do metal wires have? Why do you think these wires have a PVC or rubber-like coating? 5. Why do you think coins are made of metal? What metal do you think is used? 6. The tank is made of corrugated iron sheets. What property of metal do you think allows metal to be shaped into sheets? 7. The handle of a frying pan is made of _________. What kind of material is it? Why? Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

8. Why is the whole pan not made of plastic? Discussion and Explanation 1. The metal that the pot is made of is shiny and hard on appearance. The property of a metal that makes it shiny is called lustre. The pot also makes noise when it is dropped. This means the pot is sonorous. (Maybe now you can think about why school bells are made of metal?) 2. The most useful property of the metal, which helps the pot, is the conductivity. Metals are good conductors of heat and hence the pot gets heated up quickly for the food in it to cook. Some metals are better conductors of heat than others. 3. Metal can be drawn into long wires. This property of metal is called ductility. 4. Metal wires like those made of copper are used for electrical wiring as metal is a good conductor of electricity. To prevent people from getting a shock from the electric current, the rubber-like material is coated around the wire. This material is a non-metal, which is a bad conductor of electricity. This is also called insulation. 5. Metals are hard and strong and last longer than non-metals. This is why coins are made of metal. The type of metal used in coins, is a mixture of a few metals. This type of mixture of metals is called an alloy. 6. Metal can be pressed/beaten to form thin sheets. This property of metals is called malleability. 7. The handle of a frying pan is made of plastic – a non-metal. This is because the plastic is a bad conductor of heat and so keeps our hands from getting burned. 8. If the whole pan were made of plastic and heated it would melt right into the fire. This is because, the melting points of non-metals is much less than that of metals. It is also observed that the boiling points of non-metals are also fairly low. Non-metals do not show properties like ductility and malleability and normally break easily if the fall or if pressure is applied. This property of non-metal solids is called brittleness. Non-metals do not produce much noise on falling down and are not highly sonorous.

KEY MESSAGES: 

The simplest way to describe a metal/non metal is by looking at its physical properties (which can be seen, heard etc. when the material is in its existing/native state)  The physical properties of a metal are lustre, hardness, malleability, ductility, conductivity and sonority.  Non-metals usually exist as gases or brittle solids. They are poor conductors of electricity and have lower melting and boiling points than those of metals.

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If time permits, divide learners into groups of five for a quick evaluation – Give each group an object, which is plastic but hard/coated in shiny paint. Tell them to design an investigation in which they are trying to work out whether the object is made of metal or a non-metal. They do not need to write out the materials and apparatus required. They should explain in a paragraph about the different types of tests they would do to determine if something is made of a metal or a non-metal. Sometimes, just using one property to classify an object or material as a metal or non-metal might not be enough. For example, plastic is flexible but strong, so does this make it a metal? The answer is no. Another example is glass. Glass is also hard, but is it strong? What other properties does glass have which make it a non-metal and not a metal?

INTERESTING INFORMATION  

Mercury is the only metal that is in liquid form at room temperature. Gold is malleable enough for just 1 gram to be hammered into a sheet that is 1 square meter in size. Gold can also be made so thin that it appears transparent!

TRY IT YOURSELF 1) You may have noticed that many metals become dull over time. They can get their lustre back when treated with a cleaning agent. Different cleaning agents – natural and chemical, help in removing the dull layer from outside and give the metal its lustre back. Look around the resources at home and find the best way that you can use to clean a metal. Ask your family members how they clean metal objects to make them lustrous/shiny again? 2) DO WE EAT METAL? – Our body needs metal in small quantities called micronutrients- CHECK THIS AT HOME Write down the ingredients and nutritional information from a packet of biscuit/cereal or anything from the store. Compare. Are any of these cereals enriched with calcium, iron, zinc, etc.? What other foods do you eat that are enriched with minerals? (Bread, rice, orange Juice, etc.) What mineral nutrients are essential for human health?

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ABL 2 – CHEMICAL PROPERTIES OF METALS AND NON-METALS Activity

Learning Objective

Key Messages 

2.1

What do we mean by chemical properties of metals and non-metals?

2.2

What happens when metals and non-metals are burnt in air?

2.3

What happens when metals and non-metals react with water?

Time (min)

Properties possessed by metals and non-metals that give rise to their chemical reactions with other elements in their surroundings are called chemical properties  Elements can be more clearly classified as metals and non-metals based on their chemical properties  Some metals are more reactive than others. This is defined by the activity series.  Metals form their oxides when they react with oxygen. Metal oxides are basic in nature.  Non-metals form their oxide when they react with oxygen. Non-metal oxides are acidic in nature.



Generally, metals form theirrespective hydroxides when they react with water. Non-metals generally do not react with water. Metals give hydrogen gas when they react with dilute acid. Non-metals generally do not react with dilute acids Metals react with acids at different rates depending on their place in the activity series.

When a more reactive metal reacts

20 (this is a

  

2.4

What happens when metals and non-metals react with acids?

2.5

What happens



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when metals react with solutions of other metal salts?

with the salt solution of less reactive metal, the more reactive metal displaces the less reactive metal from its solution. ď&#x201A;ˇ

2.6

How do metals and non-metals react?

Metals and non-metals undergo a give and take reaction by transfer of electrons to form ionic compounds or electrovalent compounds. Total Time

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parallel activity with other ABLs) 10

15 Time: 10 min

ABL 2.1 LEARNING OBJECTIVE – What do we mean by chemical properties of metals and nonmetals? Note toInstructor –This section is to show that physical properties are not enough to effectively classify elements and hence chemical properties have to be studied. Make sure that the discussion is quick as it is only an introduction to the following activities.

ADVANCE PREPARATION Material List Sl.No. 1

Material Activity series chart – Chart 3

Required Quantity 1 per class

Things to Do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity We now know the different physical properties of metals and non-metals. Now let us find out if there are other differences between metals and non-metals. Procedure Ask the learners a set of leading question to explain how metals and non-metals sometimes share the same physical properties and it becomes essential to consider other properties so that we can classify them effectively. After the discussion, explain that chemical properties can be studied only by performing a series of reactions, as we will do in the next few sections. Also introduce the Activity series chart – Chart 3 at the end and explain to the learners that the order of reactivity (most reactive metals to least reactive) will occur as per this chart. Tell them that they will use the reactions as they proceed to verify this order of metals in the activity series. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

UNDERSTANDING THE ACTIVITY Leading Questions 1. In the previous ABL we compared the physical properties of so many metals. You must have noticed that some elements that are metals show properties of non-metals and vice versa. Can you give me a few examples of such cases? 2. How do we effectively classify these elements in such cases? Discussion and Explanation 1. A few examples where elements show differences from their physical properties are: a) Iodine is a non-metal but it is lustrous. b) Carbon is a non-metal but it is very hard when it is in the form of a diamond and is a good conductor of electricity when it is in the form of Graphite. c) Metals like Sodium and Potassium are soft enough to be cut with a knife and they have low melting points. 2. In such cases, we have to consider properties other than the just the physical properties. These are the chemical properties of metals and non-metals. Since the chemical properties can only be studied by conducting chemical reactions of the metals and non-metals, this is what we will be doing in the next few sections. In the case of metals, we will notice that some metals are much more reactive than others and are very excited during their chemical reactions while some metals are not. Scientists noticed that this occurs in a specific order, based on the chemical properties of the metals. They arranged the metals in this order in a series called the activity series. (Show Chart 3) We will verify this series in the following sections. Note to Instructor â&#x20AC;&#x201C; Do not go into details of each metal in the series. Just indicate the order and say it progresses from highly reactive to less reactive.

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ACTIVITY SERIES – CHART 3 (http://www.tutorvista.com/content/science/science-ii/metals-non-metals/reconcept-seriesmetals.php)

KEY MESSAGES:   

Properties possessed by metals and non-metals that give rise to their chemical reactions with other elements in their surroundings are called chemical properties Elements can be more clearly classified as metals and non-metals based on their chemical properties Some metals are more reactive than others. This is defined by the activity series.

Time: 10 min

ABL 2.2 LEARNING OBJECTIVE – What happens when metals and non-metals are burnt in air? Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Note to Instructor: Set up the experiment in ABL 2.5 before starting this ABL.

ADVANCE PREPARATION Material List Sl.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Material Piece of Magnesium wire Small bits of Copper Sulphur China dish Sprit lamp Tripod stand Wire gauze Tongs/test tube holder Safety gloves Safety goggles Sandpaper Matchbox Red and blue litmus paper Test tubes Activity series chart â&#x20AC;&#x201C; Chart 3 Glass Jar with lid Metal spatula

Required Quantity 2 per class 2 to 4 per class 10g per class 2 per class 2 per class 2 per class 2 per class 2 per class 2 per class 2 per class 1 per class 1 per class 2 each per class 2 per class 1 per class 1 per class 1 per class

Things to Do Set up the tripod next to the spirit lamp and place the wire gauze on the tripod. Place the experimental set up in a place where the learners can observe from a safe distance. Duplicate this set up. Make sure to remove any salts/dust formed on the Magnesium tape using sand paper (you can make learners do this later as well). Safety Precautions Make sure learners wear proper goggles and lab safety gear. Explain to them that many of these reactions are very violent since heating is involved and they should not take their faces close to the flame. They should also avoid smelling the gases/fumes that may be released,as the fumes can be poisonous.

SESSION Link to known information/previous activity Now that we have been introduced to chemical properties, let us look at how these elements react with air. We shall perform a reaction which will also help us verify the order of metals in the activity series. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Procedureâ&#x20AC;&#x201C; Have the learners assemble around the experiment setup. You can ask two volunteer learners to also do the reaction in duplicate along with you. Change the volunteers for each reaction. Magnesium Take a piece of Magnesium ribbon and rub it with sand paper to remove dirt from its surface (if you did not already do this in advance preparation). Place the china dish on the tripod stand. Hold the Magnesium ribbon with the help of a pair of tongs, light the Magnesium and collect the ash of burnt ribbon in a china dish. Take a moist red litmus paper and bring it in contact with the white ash (You can dissolve the ash in some water and dip the litmus in it if you wish to). Copper Put the Copper pieces in the china dish and try to burn it.Then place the dish on the tripod. Heat for about 3 minutes it till the copper turns blackish. (Sometimes, this may not happen completely, in which case you must just move on to the next reaction and explain that Copper is less reactive and it takes a long time for the reaction to take place) Sulphur Take about 5g of Sulphur in a spatula. Hold the spatula to the flame and let the Sulphur burn. Drop this spatula into a glass jar and cover it. Allow the fumes to collect in the jar for a few seconds and then drop the blue litmus into the jar. It will instantly change colour.

UNDERSTANDING THE ACTIVITY Leading Questions - Magnesium 1. How did the Magnesium look after cleaning it with sandpaper? 2. Did the Magnesium catch fire easily? Did the flame have a colour? 3. What happened to the litmus when it touched the ash? Discussion and Explanation - Magnesium 1. Magnesium is a silvery white lustrous metal. 2. Magnesium catches fire instantly and burns with a brilliant white flame and leaves behind a white ash. Here the Magnesium is reacting with Oxygen in order to burn. The Oxygen oxidizes the Magnesium to Magnesium Oxide. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Metal + Oxygen 2Mg(s) + O2

Metal Oxide 2MgO(s)

3. The red litmus turns blue. This shows that most metals form basic oxides. Leading Questions - Copper 1. How does the Copper look? 2. Did the Copper catch fire easily? Discussion and Explanation - Copper 1. Copper is an orangish-pink metal, which is highly lustrous in its pure form. 2. Copper does not catch fire and only becomes red hot on prolonged heating. This shows that copper is much less reactive than magnesium and it undergoes a much less vigorous, slow oxidation reaction when compared to magnesium. This can also be observed in the reactivity series (show Chart 3) where copper is placed much lower than Magnesium. 4Cu(s) + O2(g) â&#x2020;&#x2019; 2Cu2O(s) Leading Questions - Sulphur 1. How did the Sulphur powder look? 2. What happened when the Sulphur was burnt? 3. What happened to the litmus when it was dropped into the glass jar? Discussion and Explanation -Sulphur 1. Sulphur powder is yellow in colour. 2. Sulphur catches fire and burns with a pale blue flame and reacts with oxygen to form Sulphur dioxide gas (colourless), which has a smell of burnt matches. S8(s) + 8O2(g) â&#x2020;&#x2019; 8SO2(g) 3. The blue litmus turns red on contact with the fumes indicating that non-metals form acidic oxides. SO2 + H2O

H2SO3 (Sulphurous acid)

NOTE: Sodium and Potassium undergo violent reactions and cannot be burnt in the lab. Metals that are lower in the series do not burn and hence we cannot learn much about their reactivity by this reaction.

KEY MESSAGES: Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

 

Metals form their oxides when they react with oxygen. Metal oxides are basic in nature. Non-metals forms their oxide when they react with oxygen. Non-metal oxides are acidic in nature.

Time: 10 min

ABL 2.3 LEARNING OBJECTIVE – What happens when metals and non-metals react with water? Note to Instructor – This experiment is a demonstration but can be performed in few large groups if apparatus is available.

ADVANCE PREPARATION Material List Sl.No. 1

2 3 4 5 6 7 8 9 10 11

Material Metal samples – Aluminium, Copper, Iron, Lead, Magnesium, Zinc, Sodium, Calcium Water Sulphur Beakers/conical flasks – 250ml Sprit lamp Tripod stand Wire gauze Tongs/test tube holder Safety gloves Safety goggles Matchbox

Required Quantity One small piece of each 500ml per class 5g per class 6 per class 1 per class 1 per class 1 per class 1 per class 1 per class 1 per class 1 per class

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12 13

Activity series chart – Chart 3 Student observation sheet – Worksheet 4

1 per class 1 per group/ 1 per learner

Things to Do Make sure you collect all the necessary material and keep it handy. If you are performing the experiment in groups please account for extra safety goggles and gloves and more samples of metals. Print enough copies of worksheet – 4. Safety Precautions Learners must handle the metals with safety gloves and wear safety goggles in all experiments. Special care must be taken while handling Sodium metal. Always wear gloves and make sure it is stored under kerosene at all times. Do not expose it to air and take very tiny pieces of sodium for any reaction.

SESSION Link to known information/previous activity Now that we have seen how metals form oxides with air, let us see how they react with water. Procedure Gather the learners around the experimental setup. Give out the observation sheets. Now put small pieces of the sample (metals and Sulphur – one at a time) in beakers/flasks that are half filled with cold water.You can invite learners to do this carefully). Make sure you call out the name of the metal before you do this. Ask learners to observe each reaction and write down what they observe. (In the case of sodium, you can hold a burning match near the mouth of the flask and see if it goes out with a POP sound) Replace the water after each trial. You can use the tongs to fish out the metals that do not react with cold water. Put the metals that do not react with cold water in beakers half filled with hot water. Ask learners to observe again and note down their observations. Once the tests are complete, give the learners two minutes to discuss their observations in small groups. (Student observation sheet – Worksheet 4 for Instructor reference) NAME OF METAL

OBSERVATION – What was the reaction with water?

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UNDERSTANDING THE ACTIVITY Leading Questions 1. What happened to the metals when they were dropped in cold water? Did all the metals react in the same way? Why? 2. What happened when you put the remaining metals in hot water? 3. What happened when you put Sulphur in water? Discussion and Explanation 1. Some of the metals like Sodium react vigorously with water producing bubbles. These bubbles are hydrogen gas as the burning match held to the mouth of the flask went out with a pop sound. The metal combines with the oxygen in water to form its oxide. The metal oxide then combines with water to form its hydroxide. Metal + Water Metal oxide + water

Metal Oxide + Hydrogen (g) Metal hydroxide

2. Few metals do not react with cold water and need hot water to start a reaction. Some do not even react with hot water but may react with steam (reaction not shown) in order to form their oxide. This readiness of the metal to react with water is again determined by the activity series (show Chart 3). EXPLAIN: Metals like Sodium and Potassium that are higher up in the activity series and react vigorously with water and dart around its surface producing large amounts of heat while releasing Hydrogen. Potassium even produces enough heat for the Hydrogen gas to catch fire. In most of the reactions, we can check for the formation of hydrogen gas by holding a flame to the mouth of the reaction vessel. The hydrogen gas will put out the flame with a POP sound. 2Na(s) + 2H2O → 2NaOH(aq) + H2(g) 2K(s) + 2H2O → 2KOH(aq) + H2(g) Calcium also reacts with cold water and begins to float as the Hydrogen gas bubbles that are formed stick to its surface. Ca(s) + 2H2O(g) → Ca(OH)2(aq) + H2(g) Magnesium reacts slowly with hot water to form Hydrogen gas and white Magnesium oxide but will form its Hydroxide only on reaction with steam. Mg(s) + 2H2O(g) → Mg(OH)2(aq) + H2(g) Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Metals like Aluminium, Iron and Zinc only react with steam to produce their oxides and show no reaction with hot or cold water. 2Al + 3H2O(g) Al2O3(s) + 3H2(g) Metals like Lead, Copper, Silver and Gold do not react with water at all. These observations can be verified using the activity series. 3. Sulphur, like most non-metals under normal conditions, does not react with water.

KEY MESSAGES:  

Generally, metals form their respective hydroxides when they react with water. Non-metals generally do not react with water.

Time: 15 min

ABL 2.4 LEARNING OBJECTIVE – What happens when metals and non-metals react with acids? Note toInstructor – These reactions can be performed in large groups.Also, Non-metals are never available in their pure form and hence it is dangerous to react them with acids, as the reaction is unpredictable. Hence, we will only discuss the reaction of metals.

ADVANCE PREPARATION Material List Sl.No. 1

Material Metal samples – Aluminium, Copper,

Required Quantity 1 set per group

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2 3 4 5 6 7 8

Iron, Lead, Magnesium, Zinc, Calcium Dilute Hydrochloric acid Test tubes Safety gloves Activity series chart – Chat 3 Sandpaper Test tube stands Student observation sheets – Worksheet 5

Thermometers

240 ml per class 35 per class 5 per class 1 per class 5 small pieces 5 per class 1 per group

10 per class

Things to Do Print enough copies of Worksheet 5. Safety Precautions Learners must be careful when they are handling acid, as it can be harmful to the skin. They should always ensure to wear safety gloves while handling any chemicals in the laboratory.

SESSION Link to known information/previous activity In the lower standards, you have learned that metals react with acids to give a salt and release hydrogen gas. Let us explore if all metals react in the same way. Procedure Divide learners into groups. Give them the metals samples – 1 set to each group and quickly run them through the names of each of the metals in the set so that they are sure to recognize them. Now tell them that they will all work to observe the reaction of each of these metals with dilute Hydrochloric acid.Give out seven test tubes (each filled 1/3rd with Dil. HCl) and two thermometers to each group. Tell them to number the test tubes and note down what happens in each of the test tubes – observe the rate of formation of hydrogen bubbles carefully. Give them the student observation sheets. Tell them to drop one piece of metal in each test tube and record what they observe. Ask them to insert one thermometer into the test tubes containing Magnesium and the other thermometer into the test tube containing Copper as soon as they drop the metal into the acid. (The thermometer bulb must be fully immersed in the acid) Once they have finished, have them discuss their observations. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Student observation sheet: Worksheet 5 for Instructor reference NAME OF METAL OBSERVATION – What was the reaction with Dil. Hydrochloric acid?

UNDERSTANDING THE ACTIVITY Leading Questions 1. What did you observe when Magnesium was put in the acid? What was the reading on the thermometer? 2. What did you observe when Zinc and Iron were put in the acid? 3. What did you observe when Copper was put in the acid? What was the reading on the thermometer? 4. Do you think you can try arranging these metals in order of their reactivity based on the above observations? 5. How do you think non-metals react with dilute acids? Discussion and Explanation 1. Magnesium reacts vigorously with a stream of gas evolving. Since the reaction is so vigorous, heat is released and the temperature on the thermometer goes up. Magnesium metal dissolves readily in dilute sulphuric acid to form solutions containing the Mg(II) ion together with hydrogen gas, H2. Corresponding reactions with other acids such as hydrochloric acid also give the Mg(II) ion.

Mg(s) + 2HCl(aq) → Mg2+(aq) + 2Cl-(aq) + H2(g) 2. The reaction of Zinc is quite slow with a steady stream of gas evolved. Zn(s) + 2HCl(aq) → Zn2+(aq) + 2Cl-(aq) + H2(g) The reaction of Iron is also slow with a gentle stream of gas evolving. Fe(s) + 2HCl(aq) → Fe2+(aq) + 2Cl-(aq) + H2(g) 3. Copper does not react with a dilute acid and no hydrogen gas is produced. The reading on the thermometer remains the same. 4. Mg, Zn, Fe, .... with Cu at the end. Even metals like gold and silver do not react with dilute acids and will fall at the end of the series. (Verify using the activity series chart – Chart 3) Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

5. Generally, the non-metals do not react with dilute acids. This is because when a substance reacts with acids, it provides electrons to the H+ ions produced by the acids. Non-metals are themselves acceptors of electrons so there is no way they can donate electrons to the hydrogen ion of the acid. Hence, nonmetals in general do not react with dilute acids. (We can observe this from the fact that the thermometer glass, which is made of a non-metal,remains unaffected in the acid) However, some none metals are the exceptions which react with acid and oxidized to their corresponding oxide. Like, P, S, carbon etc. For ex: 6HNO3+ S - H2SO4+ 6NO2+ 2H2O

KEY MESSAGES:   

Metals give out hydrogen gas when they react with dilute acid. Non-metals generally do not react with dilute acids Metals react with acids at different rates depending on their place in the activity series.

INTERESTING INFORMATION: Aqua Regia – meaning: Royal water – is a freshly prepared solution of conc. HCl and Conc. HNO3 in the ratio 3:1. It can dissolve gold even though neither of these acids can do so alone. Aqua Regia is a highly corrosive, fuming liquid. It is one of the few reagents that can dissolve Gold and Platinum.

Time: 15 min + 5 min

ABL 2.5 LEARNING OBJECTIVE – What happens when metals react with solutions of other metals salts?

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Note toInstructor – this experiment can be performed as a demonstration. SET UP THIS EXPERIMENT AFTER ABL 2.1, AS IT WILL NEED 20 MINUTES INCUBATION. Discussion (5mins) can be done after 2.4 in the correct order. If you are short of time, you can set up the experiment before the class and explain the set up and just do the observation steps using the Iron nails and Copper wires to discuss.

ADVANCE PREPARATION Material List Sl.No. 1 2 3 4 5 6 7 8 9 10

Material Tongs Sandpaper Iron nails Copper Sulphate solution Beaker – 100ml Tissue paper Iron sulphate solution Copper wire Petri dish Activity series chart – Chart 3

Required Quantity 1 per class 1 per class 6 per class 100 ml per class 4 per class A few 100 ml per class Small pieces 2 per class 1 per class

Things to Do Prepare Copper sulphate and Iron sulphate solutions just before the class by taking one spatula of the powder and dissolving it in a test tube of distilled water. Safety Precautions Avoid touching Copper sulphate solution, as it is highly poisonous if ingested.

SESSION Link to known information/previous activity We have now seen how metals react with various substances ranging from air and water to acids. Here we will see how metals react with solutions of each other and try and see how to explain these reactions based on the activity series.

Procedure You can invite a few learners to help you with the experimental set up. 1) Clean three Iron nails of sufficient size by rubbing with sand paper so that their colour appears greyish. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Take sufficient quantity of Copper sulphate solution in two beakers and place them beside each other. Drop 2-3 iron nails into one of the beakers. Leave the other beaker without any nails. Keep the other remaining nails aside in a dry place for comparison after the experiment. Keep the two beakers undisturbed for about 15 min. After 15 minutes,carefully remove the Iron nail immersed in Copper sulphate solution using a pair of tongs and put it in the petri dish. 7) Repeat steps 2 to 6 to create a similar set up for the Copper wire and iron sulphate solution. 2) 3) 4) 5) 6)

Note to Instructor: while this experiment takes place, you can explain to the learners that you will discuss ABL 2.2 and 2.3 with them and then return to this experiment. After the incubation time, show the nails and Copper wires to the learners â&#x20AC;&#x201C; Pass them around and ask them to observe as they compare the experiment nail and wire to those of the control. Also ask them to observe if there is any change in the solutions used.

UNDERSTANDING THE ACTIVITY Leading Questions 1. Is there any change in the Iron nail v/s the control Iron nail? 2. Is there any change in the Copper sulphate solution v/s the control solution? 3. Is there any change in the Copper wire or the Iron sulphate solution compared to their respective controls? Discussion and Explanation 1. There is a brown coating on the Iron nail, which was dipped in the Copper sulphate solution, whereas the Iron nail placed in petri dish shows greyish colour of iron. 2. The colour of the Copper sulphate solution in which the Iron nail was dipped turns light greenish, whereas the solution of Copper sulphate in the other test tube does not change. The brown coating on the Iron nail shows that Copper is deposited on the Iron nail by displacing iron. The greenish colour of the solution in the beaker shows that Fe2+ ions are present in the solution. This shows that Iron is more reactive than Copper as Fe2+ ions have displaced Cu2+ ions from Copper sulphate solution and form light greenish coloured ferrous sulphate solution. This is a single displacement reaction in which Copper has been displaced by Iron from Copper sulphate solution and a new compound, Ferrous sulphate, is formed. So, this reaction is a chemical change. Fe (s) + CuSO4 (aq.)

FeSO4 (ap.) + Cu (s)

3. There is no change in the Copper wire or the Iron sulphate solution as the Iron is more reactive than Copper and it cannot displace the Iron from Ferrous sulphate solution. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Therefore, we can look at the Activity series (Chart 3) and conclude that more reactive metals react with solutions of less reactive metals and displace the metal from the solution.

KEY MESSAGES: 

When a more reactive metal reacts with the salt solution of less reactive metal, the more reactive metal displaces the less reactive metal from its solution .

LEARNING CHECK: The following question can be put up along with the activity series and learners can be asked to take two to three minutes in groups of 3-4 to come up with the solution as fast as possible and share it with the class. Samples of metals A, B, C and D were taken and added to the following solutions one by one. The results obtained have been tabulated as follows:

METAL

IRON SULPHATE

A B C D

NO REACTION DISPLACEMENT NO REACTION NO REACTION

COPPER SULPHATE DISPLACEMENT NO REACTION NO REACTION

ZINC SULPHATE

SILVER NITRATE

NO REACTION NO REACTION NO REACTION

DISPLACMENT NO REACTION

Use the table to answer the following questions: REFER THE ACTIVITY SERIES 1) Which is the most reactive metal?[Answer for Instructor’s reference: B] 2) What would you observe if B is added to Copper sulphate solution?[Answer for Instructor’s reference: B will displace copper from the solution] 3) Arrange the metals in their order of decreasing reactivity?[Answer for Instructor’s reference: B, A, C, D]

Time: 10 min

ABL 2.6 LEARNING OBJECTIVE – How do metals and non-metals react?

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Note toInstructor – This ABL involves knowledge of electronic configuration – referC5 - Atomic structure ABL 2. Skip detailed explanation if learners do not know electronic configuration.

ADVANCE PREPARATION Material List Sl.No. 1

Material Chart with electronic configuration of some metals and non-metals– Chart 5 (From C5 – Atomic structure Handbook)

Required Quantity 1 per class

Things to Do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity We have seen the reaction of metals with many reagents. Let us now study the atomic structure of the metal to understand why metals react in this manner. Procedure Explainbriefly how ionic compounds are formed, by referring to the chart. Explain that reactivity of elements is because they have a tendency/need to attain a completely filled valence shell. Indicate the examples in the chart and explain example of Sodium chloride. Sodium has one electron in its valence shell and Chlorine has seven. A stable atom needs eight valence electrons and hence sodium gives one electron to chlorine and the form a bond between them called an ionic bond. These compounds exist in this form and are called ionic compounds. Additional information for Instructor - In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. The positively charged ions are Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

called cations and the negatively charged ions are called anions. These can be simple ions where a single atom has a charge imbalance, or polyatomic ions made of multiple atoms. Ions in ionic compounds are held together by the electrostatic forces between oppositely charged bodies. Individual ions can have multiple nearest neighbours, so are not considered to be part of molecules, but instead part of a continuous network. Ionic compounds have high melting and boiling points, and they are hard and very brittle. As solids they are almost always electrically insulating, but when melted or dissolved they become highly conductive, because the ions are mobilized.

UNDERSTANDING THE ACTIVITY Leading Questions (these questions are only if the learners understand electronic configuration. Otherwise this ABL can be skipped with just a small explanation) 1. What is the net charge on Sodium? Why? 2. What is the net charge on Chlorine? Why? 3. Can you look at sodium and explain how it may combine with another anion, for example, Sulphate ion? Discussion and Explanation 1. The net charge on Sodium is +1 as it has one electron to give away. It is thus an ion with positive charge called a cation. 2. The net charge on Chlorine is -1 as it has to gain an electron in order to be stable. It is thus an ion with negative charge called an anion. 3. The Sulphate ion has a charge of -2. This means that one positive charge from Sodium will not be enough for it to gain stability. Hence, Sulphate combines with two Sodium ions to form Na2SO4. (Refer C5 - Atomic structure ABL-2 for formation of chemical compounds)

KEY MESSAGES: ď&#x201A;ˇ

Metals and non-metals undergo a give and take reaction by transfer of electrons to form ionic compounds or electrovalent compounds.

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ABL 3 – FROM WHERE DO WE GET METALS? Activity

Learning Objective

Key Messages 

3.1

3.2

In what form are metals present on the earth?

How do we extract less reactive metals?

Metals are present in the earth’s crust.  They may be freely present or combined with other elements to form ores based on their reactivity.  Metals/ores need to be procured from the earth by a process called mining.  The mined ore is further processed to obtain the metal. This process differs from metal to metal.  Metals that are low in the activity series are fairly un-reactive and are easily extracted.  They are present as sulphides or oxides and can be reduced to metal by heating alone. 

3.3

3.4

How do we extract moderately reactive metals?

How do we extract highly reactive metals?

Metals that are moderately reactive are slightly hard to extract as they form more stable compounds with other elements.  They are usually present as carbonates or sulphides which are heated in excess air to form their oxides (Roasting)  The metal oxides are reduced using carbon to give the free metal.  Extraction of highly reactive metals is difficult and the process is very expensive.  The only way to extract them is by a process called electrolysis.

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Time (min) 15

ď&#x201A;ˇ

3.5

What is corrosion and how do we prevent it? ď&#x201A;ˇ

Corrosion is the gradual destruction of materials (usually metals) by chemical reaction with its environment. Commonly, this means chemical oxidation of metals in reaction with an oxidant such as oxygen. Corrosion can be prevented using methods like painting, galvanizing, alloying etc Total Time

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10 (Falls within the time of 3.4)

35 Time: 15 min

ABL 3.1 LEARNING OBJECTIVE – In what form are metals present on the earth? Note toInstructor – This ABL deals exclusively with extraction of METALS. We will not be touching upon non-metals, as that will require us to talk in detail about carbon and its compounds, which is beyond the scope of this handbook.

ADVANCE PREPARATION Material List Sl.No. 1

Material Flip charts of metal objects – school bus, switch, trumpet, bicycle – Chart 5 Activity series chart – Chart 3

Required Quantity 1 per class

1 per class

Things to Do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity We have seen the various kinds of metals and how they react. Have you ever wondered how we use these metals in our daily lives and from where we get these metals? Procedure Show the learners the flip charts (Chart 5) and divide them into four groups. Give each group a chit with the leading question and discussion point for one of the objects. (Group 1 – School bus, Group 2 – Trumpet, Group 3 – Bicycle and Group 4 – Switch) Ask the learners to discuss the points on their chit and then come back and discuss it with the class. Once all the groups have done this, discuss leading question 5 with the whole class. Lead them to the conclusion that the products they use in their daily life are made of raw materials. These materials are like wood, rock, metals etc. Many metals are bought and sold as raw material and Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

different things are made from them. One metal can have many uses based on what product it is used in.

UNDERSTANDING THE ACTIVITY Leading Questions 1. 2. 3. 4. 5.

What is a school bus used for? What is it made of? Is it only made of one kind of raw material? What is a musical instrument like a trumpet made of? What is a bicycle made of? Why does a light bulb come on when u turn on the switch? How do you think we get these metals? Do we get all metals in the same way?

Discussion and Explanation 1. A school bus is used as transportation to get to school. It is made up of various raw materials like metal and glass and rubber etc. The common metals used in a school bus are Steel – an alloy of Iron with small amounts of Chromium and Carbon which forms the body and engine of the bus and the smaller parts are made of Aluminium which is light weight and easy to work with.An alloy is a metal made by combining two or more metallic elements, especially to give greater strength or resistance. 2. A trumpet is made entirely of Brass – which is an alloy of Copper and Zinc. The most common type of Brass used is yellow Brass, which is 70 percent Copper and 30 percent Zinc. Some small manufacturers will use such special brasses as Ambronze (85 percent Copper, 2 percent Tin, and 13 percent Zinc) for making certain parts of the trumpet (such as the bell) because such alloys produce a sonorous, ringing sound when struck. Some manufacturers will silver- or goldplate the basic brass instrument.Very little of the trumpet is not made of brass. 3. Bicycles use a lot of metal in their structure. The frame of the bicycle is made of light Aluminium. The more expensive and long lasting ones are made of alloy Steel or Titanium. The bicycle chains etc are all made of stainless Steel. These metals are cheap enough to produce in large quantities as well. We can’t imagine using metals like Gold to make a bicycle, as we would not want to pay lakhs of rupees for a cycle! Also, Gold is a very soft metal that will not have the strength to bear the weight of a person or last the wear and tear of transport. 4. All the bulbs in the house are connected to the switch by a wire. This wiring is present throughout the house and in most electrical appliances in the house. How many light switches will you need in your lifetime? Each one is wired with Copper. Copper wiring is also found in appliances, computers, televisions, etc. Can you guess how much metal each of us must be using in a lifetime? (Tell learners that they will discover the answer soon) 5. We get metals from the earth. Metals, like many raw materials are natural resources. These natural resources are often found in the earth’s crust. They may occur in their natural state or combined with other substances in the form of mineral ores. The simplest definition of an ore is a mixture of a metal containing mineral and other materials ('minerals') from the surrounding rocks. Metal ores are Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

obtained by mining and that this may involve digging up and processing large amounts of rock. These ores are then separated from other impurities by various methods (REFER C2 -SEPARATION TECHNIQUES ABL) Ores are often oxides, carbonates or sulphides. These ores are all finite resources so we should use them wisely! Any ore must contain enough of the metal to make it worthwhile to mine and then extract the metal.Since the majority of metals are found combined with non–metals like Oxygen (oxide ion) or Sulfur (sulfide ion) or the carbonate ion, chemical reactions are needed to free the metal from its mineral source/ore. Metals form ores based on their reactivities (as we studies in the previous ABL). Based on their position in the activity series (Chart 3), metals are grouped into three sections – less reactive, moderately reactive and highly reactive. The difficulty in extracting them also increases with their reactivity.(The more reactive the metal, the harder it is to extract). Based on the chemical reactions that we studies in the previous ABLs we have different methods employed to extract different metals based on their reactivity. Some non-reactive metals like Gold and Platinum are found in their native state and do not require any extraction at all!

KEY MESSAGES:    

Metals are present in the earth’s crust. They may be freely present or combined with other elements to form ores based on their reactivity. Metals/ores need to be procured from the earth by a process called mining. The mined ore is further processed to obtain the metal. This process differs from metal to metal.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the key messages chart. If you have time during the class, make up a small game or quiz or match the following as a learning check. This may have to be done as part of advance preparation. OR 1) Explain where we get metals from? 2) What is an ore? Answers for Instructor’s reference – 1) We get metals from the earths crust where it is present in the form of ores. These ores are mined and processed before we can use chemical processes to extract the metals from them. 2) The simplest definition of an ore is a mixture of a metal containing mineral and other materials ('minerals') from the surrounding rocks.

Time: 10 min

ABL 3.2 Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

LEARNING OBJECTIVE – How do we extract less reactive metals? Note toInstructor – this experiment can only show the learners the reaction that takes place in a laboratory, which is never exactly the same as that in a factory. Industrial process of extraction can be shown to the learners by going to the video links provided.

ADVANCE PREPARATION Material List Sl.No. 1 2 3 4 5

Material Activity series chart – Chart 3 Boiling Test tube Test tube holder Copper sulphide – Chalcocite / copper glance Bunsen burner

Required Quantity 1 per class 1 per class 1 per class 5g per class 1 per class

Things to Do Not Applicable Safety Precautions These reactions produce a lot of heat and toxic gases like SO2. Students must only observe from a minimum of five feet distance. Make sure you do not take too much Copper sulphide initially to minimize the amount of SO2 formed.

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FIGURE 1 – ACTIVITY SERIES for Instructor reference Tell them you will take Copper as an example to show them how the less reactive metals are extracted. Demonstrate the experiment and them explain the process as follows: For this reaction – take Copper sulfide (Chalcocite/ copper glance - 5g) in a boiling test tube and heat over the flame for about five minutes till black powder turns red hot – at this point you can stop to see the blackish mass of Copper oxide formed. Keep over flame for another minute and remove and cool. You should be able to observe brownish pellet like masses of Copper formed. (Make sure not to allow learners to go very close to the mouth of the test tube, as SO2 can be toxic.) Explain the following with reference to the above reaction: Note to Instructor: you can ask leading questions that are relevant during the explanation. Copper is usually found as a sulphide ore called Copper pyrites. This is cleaned and separated to finally get Copper sulphide. This Copper sulphide can be heated in excess of air (Oxygen) to give Copper (Thermal decomposition). The reaction is as follows: 2Cu2S + 3O2 2Cu2O + 2SO2 2Cu2O + Cu2S 6Cu + SO2 The Copper sulphide gives Copper oxide, which further reacts with the remaining mixture to give Copper.

Show the video of the Industrial process and explain wherever possible. INDUSTRIAL PROCESS:ADD VIDEO LINK Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

The traditional method of extraction is to heat the copper sulfide. Copper(II) sulfide gives Copper and Sulfur dioxide during thermal decomposition. Thermal decomposition means that the compound breaks down into other substances when it is heated. Thermal decomposition is an endothermic reaction. Copper(II) sulfide Copper + Sulfur dioxide CuS(s) Cu(s) + SO2(g) The impure Copper which results is called blister Copper.To ensure that the reaction occurs smoothly, a reducing agent like Coke may also be added. The disadvantage of this method is that it uses a lot of energy. If Sulfur dioxide escapes into the atmosphere it causes pollution. The advantage is that it is fast. Today, other methods of extraction are also used like displacement of copper from its ore by reaction with a more reactive metal like Zinc.

UNDERSTANDING THE ACTIVITY Leading Questions (ask learners to the refer to the reaction you have explained to answer) 1. 2. 3. 4.

What was the initial powder we heated? What did it form at the middle of the reaction? What is the end product we aim to get? How many steps did this reaction take to perform?

Discussion and Explanation 1. The initial powder heated was Copper sulphide. This is a representation of other sulphide ores of Copper like Copper pyrites, which is the most commonly occurring form that is used in industries. (Show video of industrial process of extraction.) 2. The middle product is Copper oxide that is formed on reaction with the Oxygen present in the air. 3. The end product is Copper. This Copper is not completely pure and needs to be further refined by methods like electrolysis etc. 4. This was a simple one step process that only involved heating at high temperatures to enable thermal decomposition of the Copper ore as Copper is a fairly un-reactive metal that is placed low in the activity series.

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KEY MESSAGES:  Metals that are low in the activity series are fairly un-reactive and are easily extracted.  They are present as sulphides or oxides and can be reduced to metal by heating alone.

LEARNING CHECK: There will be a combined learning check for ABL 3.2, 3.3 and 3.4 at the end of ABL 3.4.

INTERESTING INFORMATION: Copper after extraction has many uses: 

It is used in making electrical cables and wires.



It is used in making coins.



It is used in making alloys like brass, German silver, constantan, bell metal etc.



It is used in making utensils – Copper bottom vessels.



It is used in making scientific equipments like calioriemeter boilers etc.

TRY IT YOURSELF: Try and find Copper objects in your surroundings and make a list of all the applications of Copper.

Time: 10 min

ABL 3.3 LEARNING OBJECTIVE – How do we extract moderately reactive metals?

ADVANCE PREPARATION

Material List Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Sl.No. 1 2 3 4 5 6 7

Material Activity series chart – Chart 3 Lead oxide – litharge Charcoal Crucible lid Tripod stand Wire gauze Bunsen burner

Required Quantity 1 per class 10g per class 10g per class 1 per class 1 per class 1 per class 1 per class

Things to Do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity We have seen in the previous ABL that metals are extracted by different procedures based on their position in the reactivity series. Now let us see how the moderately reactive metals are extracted. Procedure Show the learnersthe metals that fall under the moderately reactive bracket in Chart 3. (Zinc to Lead) Tell them you will take Lead as an example to show them how the moderately reactive metals are extracted. Demonstrate the experiment and then explain the process as follows: For this reaction – place two spatulas of the yellow Lead oxide with the same amount of powdered charcoal and place the mixture on a crucible lid supported by a wire gauze and tripod stand. Heat the mixture strongly for about five minutes. For better results, hold the Bunsen burner in your hand so that the tip of the inner blue flame touches the mixture. When this is done, cool it and examine the mixture carefully. Can you see any Lead particles? In some cases you may have one or two larger particles with which you can demonstrate the marking of paper as proof of Lead extraction. Explain the following with reference to the above experiment: Note to Instructor: You can ask leading questions 1 and 2 during the explanation. Many metals that are in this category are found in oxide form in their ores. These oxides can be reduced by Hydrogen (as you may have studied in lower grades about hydrogen gas as a reducing agent). A better Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

way to do this may be to use Carbon in the form of charcoal or coke as it is a stronger and cheaper reducing agent than Hydrogen. Lead is found in its oxide form (Lead oxide) in its ore more commonly called litharge. This Lead oxide is reduced in the presence of coke/charcoal to give molten Lead. The most common Lead ore that is found called Galena (Lead sulphide), which is combined with Zinc, Silver etc. This ore is treated and melted to get Lead sulphide. This Lead sulphide is then burnt (at very high temperatures) in excess air to give Lead oxide. This oxidation process is called Roasting (also called sintering). 2 PbS + 3 O2 2 PbO + 2 SO2 This Lead oxide is then reduced to give molten lead using Carbon (charcoal) as a reducing agent. (This process is called smelting) 2PbO + C

2 Pb + CO2

Explain that the procedure you demonstrated is only the second step of the process as the first step requires very high temperatures – up to 1000oC, which cannot be effectively produced in a laboratory.

UNDERSTANDING THE ACTIVITY Leading Questions (ask learners to the refer to the reaction you have explained to answer) 1. 2. 3. 4.

What was the initial powder we heated? What did it form at the end of the reaction? What is the end product we aim to get? How many steps did this extraction take to perform? Which steps did you observe?

Discussion and Explanation 1. The initial powder that was heated was Litharge (Lead oxide), which is yellow in colour. 2. At the end of the reaction, grey flecks of Lead were formed. 3. The end product we wish to extract is Lead but however, this is not Lead in its purest form and needs to be treated further. Pure Lead is obtained with large amounts of heat in industrial processes to give molten Lead. (Show industrial manufacturing video) 4. This reaction takes two steps to extract the metal – roasting with Oxygen and reduction with charcoal. We observed only the second stage in the process. Note – this method of extraction is applicable to the less reactive metals as well.

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 

Metals that are moderately reactive are slightly hard to extract as they form more stable compounds with other elements. They are usually present as carbonates or sulphides which are heated in excess air to form their oxides (Roasting). These oxides are further reduced (with a reducing agent) to give the free metal.

LEARNING CHECK: There will be a combined learning check for ABL 3.2, 3.3 and 3.4 at the end of ABL 3.4.

Time: 25 min

ABL 3.4 LEARNING OBJECTIVE – How do we extract highly reactive metals? Note toInstructor – This experiment is performed exclusively as a demonstration Learners will have to have a basic knowledge of the behaviour of charged particles – 1) Ionic compounds split up into their respective charged particles in solution. 2) Positively charged ions are cations and negatively charges ions are anions. 3) Unlike charges attract. The electrolysis process takes about 15-20 minutes once the current is switched on. In this time, you can progress to ABL 3.5 and return for the discussion.

ADVANCE PREPARATION Material List Sl.No. 1 2 3 4 5 6

Material Activity series chart – Chart 3 Copper sulphate solution Clean Copper plate Beaker (1000 ml) Metal object – spoon Battery

Required Quantity 1 per class 500ml per class 1 per class 1 per class 1 per class 1 per class

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7 8

Tissue Stands with clamps

4 per class 2 per class

Things to Do Set up the experimental apparatus as shown in the figure and prepare copper sulphate solution and keep aside. Make sure you connect the battery such that the copper plate is the anode and the metal object is the cathode.

FIGURE 2 â&#x20AC;&#x201C; Extraction of Copper by Electrolysis

Safety Precautions Not Applicable

and explain that the electrolyte must be a solution of the metal to be extracted (In this case – Copper sulphate). The cathode must have a base for the pure metal to be deposited. This base can be another metal to be plated like the spoon or a pure strip of the metal to collect more pure metal on it. The anode can be the impure metal (Copper plate here). Make sure the two electrodes are connected to the battery. Wipe them down with tissue and immerse them in the Copper sulphate solution in the beaker. Use the clamps and stand to keep the electrodes suspended in the solution. Now connect the battery to the power supply and pass a small current for several minutes until the object becomes plated with Copper. Switch off of the power supply and show the learners the spoon, which was at the cathode and discuss. Explain with reference to the above experiment: The metals high up in the reactivity series are very reactive. They cannot be obtained from their compounds by heating with Carbon. For example,Carbon cannot reduce the oxides of Sodium, Magnesium, Calcium,Aluminium, etc., to their respective metals. This is because these metalshave more affinity for Oxygen than Carbon. These metals are obtainedby electrolytic reduction. For example, Sodium, Magnesium and Calciumare obtained by the electrolysis of their molten chlorides. The metalsare deposited at the cathode (the negatively charged electrode), whereas,chlorine is liberated at the anode (the positively charged electrode). Thereactions are – At cathode Na+ + e- → Na At anode 2Cl- → Cl2 + 2eThe method of electrolysis can be used to extract any metal in its purest form but is limited only to the highly reactive metals as it is a very expensive process.

UNDERSTANDING THE ACTIVITY Leading Questions (ask learners to the refer to the reaction you have explained to answer) 1. What do you observe on the spoon? Why? 2. Why do we insist that the electrolyte should be a solution of the metal? 3. What happens to the Sulphate ions in the solution? Discussion and Explanation

1. The spoon has a layer of pure Copper coated on it. As the Copper ions are positively charged, the get attracted to the negatively charged electrode (cathode) and het deposited on it. 2. The electrolyte splits up into its respective ions – Cu2+ and SO42- in the solution. The Copper ions in this state are extracted when they get deposited on the cathode. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

3. The Sulphate ions have a negative charge and are hence attracted to the positive electrode and migrate to the anode. In this manner we can extract highly reactive metals from their ores. This method is applicable for the extraction of any metal as long as it can be done affordably.

KEY MESSAGES:  

Extraction of highly reactive metals is difficult and the process is very expensive. The only way to extract them is by a process called electrolysis.

LEARNING CHECK: Divide learners into groups of 5 or 6 and tell them that they will now get a chance to be extraction engineers! Tell them that each group will get a slip of paper with the name of an ore on it. They will have to discuss what they learnt and come up with a suitable procedure to extract the metal from the ore. They will only get five minutes to come up with some general steps. (Remind them that it is all about understanding where the metal falls in the reactivity series). Tell them it does not matter if it will really work and so they can assume things like temperature of heating etc. You can review their answers/ have them present their extraction steps quickly or just go around helping the groups and correcting them as they work to help them understand. Some ores that you can write down on slips of paper for the learners Salt – NaCl – this is the most common source from with we extract sodium Bauxite – Al2O3.2H2O Chalcocite – Cu2S Cuprite – Cu2O Pyrite – FeS2 Galena – PbS Sphalerite –ZnS Answers for Instructor’s reference:

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1) Copper/Silver ores – these can be extracted by one step procedures of thermal decomposition. They can also mention reduction with Carbon if necessary 2) Iron/Zinc/ Lead ores – these have to be two step extraction procedures with roasting followed by reduction with carbon 3) Sodium/Potassium/Calcium/Magnesium/Aluminium – electrolysis procedure only. Tell them to think of what they can use as an electrolyte in the process. What will be the anode, cathode etc? Certain learners with prior knowledge may use a displacement reaction in order to extract a metal – you can accept this process but must cross check that a more reactive metal is displacing a less reactive metal.

Time: 10 min

ABL 3.5 LEARNING OBJECTIVE – What is corrosion and how do we prevent it? Note toInstructor – This ABL may be taught while you wait for the electrolysis experiment to occur in ABL 3.4.

ADVANCE PREPARATION Material List Sl.No. 1 2 3 4 5 6

Material Activity series chart – Chart 3 Rusted nails/bottom of a ship or a metal bridge (picture) Old Copper that has gone green (picture) Blackened Silver vessel or jewellery (picture) Iron vessel and steel vessel – pictures Applications of alloys handout

Required Quantity 1 per class 1 per class

Making of metal alloys video http://www.ndep.us/Making-Metal

Optional

1 per class 1 per class 1 pair per class 1 per learner

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Things to Do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity We have learnt all about metals and their reactions in the previous ABLs. Some of these reactions occur commonly in our environment. Let us look at the most common reactions that metals undergo in our environment. Procedure Note to Instructor - This procedure is a series of discussions with the learners that must progress quickly and in this order. Ask leading question and discuss point 1 and then move on to 2 and so on. 1) ACTIVITY 1 Show the learners the picture of the corroded Iron, Copper and Silver. Ask them what is common between them.

Rusted Iron

Corroded Silver

Corroded Copper

2) ACTIVITY 2 After introducing corrosion, tell them that there are ways to prevent it. Ask them if they have ever seen people in their surroundings ever doing anything to protect metal objects from the environment. 3) ACTIVITY 3 Explain the concept of alloys by showing them the iron and steel vessels and ask them which they would prefer to cook in. 4) ACTIVITY 4 Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Give learners the handout on a few applications of alloys and give them about five minutes to read through it and ask them to answer a few questions (have a quiz if there is time). Note to Instructor – Step 4 can be done after discussion the electrolysis procedure of ABL 3.4

UNDERSTANDING THE ACTIVITY Leading Questions ACTIVITY 1 1. 2. 3. 4.

What do you see in common between these three pictures? Why do you think this happens? Are you allowed to touch a rusted object? Why not? Why doesn’t Gold corrode?

Discussion and Explanation ACTIVITY 1 1. All three pictures show metals that look damaged. 2. This happens because the metal reacts with the environment to form other compounds. This process is called corrosion. The metals undergo a chemical reaction with other elements present in the environment to form compounds. This is usually a slow and steady reaction. Examples of corrosion – Picture 1 – Iron articles are shiny when new but react with air (Oxygen) and water in the environment to form Iron oxide, which is a reddish brown compound that we all commonly call rust. This process is commonly called rusting. Picture 2 – the green coating on Copper metal is called Patina. This is a coating of Copper carbonate formed by a reaction of Copper with water and Carbon dioxide from the air. Picture 3 – Silver is a little harder to corrode but in environments where the air has traces of Hydrogen sulphide or Ammonia, Silver forms a blackish coat of Silver sulphide. 3. We are not allowed to touch rusted objects because they form a home for very harmful disease causing bacteria that can enter our body and causes a deadly infection called tetanus. If we get cut by a rusted object, we must make sure to get an anti-tetanus injection at the hospital immediately to prevent this infection. 4. Since corrosion processes are also chemical reactions, the metals towards the top of the activity series have a higher tendency to react with the environment. Therefore metals like Gold do not corrode and remain in their shiny state even on long periods of exposure to the environment. Leading Questions

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ACTIVITY 2 1. Is there any way to prevent this corrosion? Have you seen people in your family or your friends doing anything to protect metal? Discussion and explanation ACTIVITY 2 1. We prevent corrosion by keeping the metal away from moisture, Carbon dioxide and Oxygen as much as possible. This is achieved by the following methods: a) Coating metals with paint to keep out air and moisture b) Coating metals with other less-reactive metals ex: galvanizing – coat Iron with Zinc that prevents it from rusting by forming a protective carbonate layer on the surface of the iron. Electroplating is another way of doing this by coating one metal on another by the process of electrolysis. Some forms of electroplating like silver and gold plating are also done for decorative purposes on jewellery etc. En example of electroplating was shown in activity 3.4 – Copper was electroplated on a metal spoon. c) Alloying – this a method of combining metals in different ratios to create a kind of super-metal that will have the desired qualities of both metals. Alloyed metals are stronger and more resistant. We will see this in the next section. Leading Questions ACTIVITY 3 1. What does one prefer to cook in? The Steel vessel or the Iron vessel? Why? 2. How do we get Steel? Discussion and explanation ACTIVITY 3 1. We prefer to cook in the Steel vessel rather than the Iron vessel because it does not rust or get damaged for a long time and it cooks the food much faster. It is also lighter to carry and has a clean, shiny and smooth appearance. 2. Steel is an alloy of Iron and Carbon with small amounts of Chromium. It is much stronger and more resistant to corrosion than Iron. ACTIVITY 4 Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

Questions are mentioned in the handout with a solution sheet for the Instructor.

KEY MESSAGES: 



REFERENCES: 1) National Council of Educational Research and Training, Class X, November 2012 2) Stage 1 – Chemistry – ‘O’ level – Nuffield foundation, Heinemann Educational Books Ltd., 1978

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53 WORKSHEET 1

1. You can see that house A and B are built of different materials. What material was used to build house A?

2. What material was used to build house B?

3. If you had to build a house next to the sea, which would you choose, House A or B? Why?

4. Write down at least three other materials that could be used for building a house or parts of a house.

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WORKSHEET 3 STUDENT NAME: METALS

Name of the object

How the objects feels when I touch it

What the object looks like

The sound that the object made when I dropped it/ tapped it on the ground (learners can spell the sound if they like)

NON-METALS

Name of the object

How the objects feels when I touch it

What the object looks like

The sound that the object made when I dropped it/ tapped it on the ground (learners can spell the sound if they like)

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55 WORKSHEET 4

STUDENT NAME:

NAME OF METAL

OBSERVATION â&#x20AC;&#x201C; What was the reaction with water?

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56 WORKSHEET 5

STUDENT NAME:

NAME OF METAL

OBSERVATION â&#x20AC;&#x201C; What was the reaction with Dil. Hydrochloric acid?

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ATOMIC NUMBER

ELECTRONIC CONFIGURATION DIAGRAM

ELECTRONIC CONFIGURATION IN WORDS

1 1 2

2,1

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2,2

2,3

2,4

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2,5

2,6

2,7

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2,8

2,8,1

2,8.2

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2,8,3

2,8,4

2,8,5

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2,8,6

2,8,7

2,8,8

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APPLICATION OF ALLOYS

Alloys are metals made up of more than one element. Alloys serve people in many ways. Alloys are valuable because they can be made stronger, harder, lighter or better than pure elements. Most of the metals we come in contact with in our daily lives are alloys. Alloys can be made up of two or more metals, or of metal elements mixed with non-metallic elements like Carbon, Sulfur, Boron or Silicon. For instance, Steel is actually an alloy of iron and carbon, while stainless steel is an alloy of Iron, Carbon, Nickel and Chromium. Very few metals are used today in their pure elemental form. Two of the earliest alloys devised by humans combined Copper and Zinc to make Brass, and mixed Copper with Tin to produce Bronze. These ancient alloys still serve humans today. Pewter is an alloy of Tin and Lead. Even the familiar Pepsi/Coke can is actually made from an alloy of Aluminum and Manganese. And the coins in your pocket are an alloy of Copper and Nickel. Making Alloys There are several different techniques for making alloys. A common technique is to melt the alloy elements together, which is how most iron and copper alloys are made. Another common alloy-manufacturing technique is called sintering, in which powdered forms of the specified elements are mixed together, then squeezed under extremely high pressure and heated until they fuse together into an alloy. Other techniques include electroplating etc. Uses of Aluminum Alloys: Aluminum when combined with other metals gives strength and specific characteristics for a particular use. Aluminum alloys are extensively used in the production of cars and engine parts. The vast range of quality Aluminum is used in various applications like transport, packaging, electrical application, medicine, and construction of homes and furniture. Aluminum alloys have their biggest application in airplane parts as they are lightweight and can bear high pressure. There are more than 300 alloys of Aluminum. Uses of Copper Alloys: Copper alloys have exceptional electrical and thermal performance, good corrosion resistance, high ductility and relatively low cost. Copper alloys are used in the manufacture of all types of electrical equipment. Uses of Nickel Alloys: Nickel alloys have good corrosion resistance and heat resistance. Nickel alloys are used for a wide variety of applications like aircraft gas turbines, nuclear power systems and widely used in chemical and petrochemical industries. Amalgam: Alloys of precious metals with mercury are called Amalgams. Amalgams are used for plating different objects with precious metals like Gold and Platinum. Uses of Stainless steel Alloys: In order to reduce corrosion losses, there are extensive uses of stainless steels. Stainless steel alloys are used for many commercial applications such as watchstraps, kitchen vessels, tanks, big Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com

64 containers etc. Stainless alloys used for making tubes intended for placement on the bottom of the sea. Uses of Gold alloys: We usually alloys Gold with Copper and Silver for use in jewelry. By varying the amounts of the different metals we can get different coloured gold objects. Also, gold is a very soft, delicate metal to work with. Alloying it makes it harder and stronger for making intricate jewelry. Pure gold is 24 Carat gold. When we see 22 Carat or 18 Carat it means that the Gold has been alloyed with other metals in different proportions. Shape Memory Alloy: (SMA, smart metal, memory metal, memory alloy, muscle wire, smart alloy) is an alloy that â&#x20AC;&#x153;remembersâ&#x20AC;? its original, shape. If we bend these alloys and then heat them, they will return to their original shape. These alloys are used by doctors, in making braces to fix the arrangement of our teeth and to treat fractures in broken bones. They cool the alloy and wrap it around the broken bones and when the alloys heat up then go back to their original shape and pull the bones together. REFERENCES: http://www.ehow.com/about_6742426_uses-alloy.html http://www.ehow.com/list_6708135_different-types-alloys-use.html http://en.wikipedia.org/wiki/Shape_memory_alloy

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65 QUIZ/REVIEW QUESTIONS: 1) True or false? a) An Alloy can be made only by mixing two or more metals together. (Answer – False: Alloys can be made by mixing any elements together, metals and non-metals) b) Copper is used in building an Airplane. (Answer – False: It is not strong enough to build the body of a plane.) c) The most common alloy of Iron is Stainless steel. (Answer – True) d) There are more than 300 Alloys of Aluminum. (Answer – True) e) 22 Carat gold is pure Gold. (Answer – False: Pure Gold is 24 Carat Gold) 2) Some alloys can remember their original shape when they are heated after bending. What are these called? (Answer – Shape memory Alloys) 3) Where are Shape memory alloys normally used? (Answer - They are normally used by Doctors to fix bones and teeth) 4) Which metal is common in all Amalgam alloys? (Answer -Mercury) 5) What is the method called when we manufacture an alloy by mixing powdered elements under high pressure? (Answer – Sintering) 6) Alloys of which metal are known for being lightweight? (Answer – Aluminum alloy) 7) How much metals does an average human being use during his/her lifetime? a) 10 Kg b) 1000 Kg c) 50000 Kg d) 900000 Kg (Answer – d : AN AVERAGE HUMAN BEING USES 0.9 MILLION KGS OF METAL IN HIS LIFETIME!! (www.mineralseducstioncoalition.org)) 8) Match the following: a) Iron

1) Patina

b) Copper

2) Sulphide coat

c) Silver

3) Rust

(Answer – a-3, b-1, c-2) 9) Name a metal that does not corrode easily. (Answer – Gold/Platinum) 10) If you fall down and get cut on a rusty fence, what will you do? a) Get up and forget about it. b) Wash the cut and leave it. c) Hide it from your mother. d) Go to the doctor and get a tetanus injection. Agastya International Foundation. For Internal Circulation only. Request to Readers- Kindly mail details of any discrepancies to handbooks.agastya@gmail.com