Unit 7 – Properties of Matter

7Properties of Matter

In this chapter you will ...

• describe and classify matter.

• test and describe the properties of materials.

What are some properties of matter and materials?

Go Online!

Access interactive content relating to this topic on the NGScience website.

ngscience.com

What properties of objects make them suitable to their use?

What Is Matter?

Everything around you is matter. The things you see, touch, smell and taste are matter. The water you drink is matter. The air you breathe is matter too. Matter is anything that has mass and takes up space.

What matter can you see around you? Is there matter around you that you cannot see?

The soft toy takes up space in the bucket. The beach ball takes up more space than the toy car.

Water, rocks and air are matter.

Some matter can have more mass than other matter. Using a balance, we can see that the teapot has more mass than the mug.

Try This!

Compare some different objects in your classroom. What words can you use to describe each object?

States of Matter

Compare the things on these pages. How are they different?

Matter can come in different states – solids, liquids and gases. The toy blocks are solid matter.

Water is liquid matter. The air inside the balloon is gas.

AB Activity 7.1

Solids

Take an eraser and roll it on a table. Does the shape of the eraser change?

Think Deeply

Find three things in your classroom that are solid matter. Tell how you know they are solid matter. The eraser, like most of the things you see around you, is solid matter. Solid matter has a shape of its own. The amount of space solid matter takes up does not change. When you rolled the eraser on the table, the shape and amount of space taken up by the eraser did not change.

Ice is solid water.

The toy blocks are solid matter. They keep the same shape when they are in the container or spilled out. The amount of space the toy blocks take up also stays the same.

AB Activities 7.2 – 7.3

Try This!

Pour some water between different containers. Describe what happens to the shape of the water.

Think Deeply

A pile of sand appears to change shape as it is poured from one container to another. Is sand a solid or a liquid? Explain your answer.

Liquids

What happens to the shape of the water as the girl pours it from one container to another?

The colored water the girl is pouring is liquid matter. As the liquid is poured from one container to another, its shape changes. Liquid matter does not have a shape of its own. A liquid flows to take the shape of the container it is in.

Pour some water into a beaker. Observe how much space the water takes up. Pour the water into another container, then pour it back into the beaker. What do you notice? Like solid matter, the amount of space taken up by a liquid does not change.

Tell how you know milk is a liquid.

AB Activities 7.4 – 7.5 Did You Know?

The amount of space something takes up is called volume. You can measure the volume of liquids with a measuring cup or beaker.

When air is let out of a balloon, it spreads out to fill the room.

Gases

Blow up a balloon and hold it closed. Observe the shape and size of the balloon. Slowly let the air out of the balloon. What do you observe about the size and shape of the balloon? The air in the balloon is a gas. Gas is matter that does not have a shape of its own. It spreads out to fill the space it is in.

Try This!

Blow some soap bubbles. Talk about the shape and size of the bubbles. What happens to the air in the bubbles when they pop?

Think Deeply

Gases can also change in the amount of space they take up. When you let the air out of the balloon, it spreads out to fill the room. It takes up more space.

A scuba tank can hold enough air for a diver to breathe underwater for more than an hour. Why is this so?

Properties of Matter

Describing and Measuring Matter

Describing Matter

We can describe and compare the objects around us by observing their properties. We can observe some properties, such as shape, size and color, using our sense of sight.

What are some of the properties of the objects on these pages?

Try This!

Use your sense of touch to observe different objects in your classroom. Describe the texture of each object.

You can also observe the properties of objects using your sense of touch. Texture is how an object feels. An object might feel hard or soft. It may feel rough or smooth.

AB Activity 7.6

Try This!

Use a balance to compare the weight of the objects on your table. Order the objects from the lightest to the heaviest.

Measuring Matter

Compare the soft toy and the soccer ball. Which object has more mass? How do you know? There are many properties of objects you can test or measure. A balance is a tool you can use to measure the weight of an object. Weight is how light or heavy something is.

AB Activity 7.7

The soccer ball is heavier than the soft toy.

Rulers and tape measures can be used to measure the length of objects in centimeters or inches.

You can test if an object is magnetic by holding it near a magnet. A magnetic object is pulled by the magnet. You can test the buoyancy of an object by placing it in water. Some objects stay on top, or float, when placed in water. Other objects fall to the bottom, or sink, when placed in water.

The nails are magnetic.

The rubber duck floats. The marbles sink.

AB Activities 7.8 – 7.9

Go Online!

Learn about different materials and their properties on the NGScience website. QuickCode: P9G5

Try This!

Find objects in your classroom that are made of two or more different materials. How are the materials suited to how the objects are used?

Properties of Materials

We use different materials to make different objects. Some materials include metal, glass, wood, plastic, rubber and fabric.

Different materials have different properties. When we make objects, it is important to choose materials that have properties that are suited and safe for how the object is used.

What materials are used to make these objects? How are the properties of the objects suitable to their use?

The strength of a material is how Strength goes here. much it can be pulled apart or pushed together without breaking. Flexibility goes here. Hardness is how much a material can withstand scratching.

Why is metal a suitable material for making things such as bridges, hammers and nails?

Flexibility is how much a material can bend without breaking. The rope is made of material that is flexible and strong.

What are some other objects that are flexible? What materials are they made of?

Transparency is how much light can pass through a material. The glass jars are transparent. You can see the food inside the jars clearly. The white curtains allow some light to pass through – they are translucent. You can see through the curtains, but not clearly. A material that does not allow any light to pass through it is opaque. You cannot see through opaque materials.

Absorbency is how much liquid a material can hold.

Sometimes, like when cleaning a spill, it is useful for a material to be absorbent.

Other times it is helpful to use materials that are not absorbent, like the plastic used to make an umbrella and a raincoat.

AB Activities 7.10 – 7.11

Discuss the materials used to make these objects. How are the materials suitable and safe for how the objects are used?

Engineer It!

Design and build your own object. Select materials based on how suitable and safe they are for the function of the object.

Science Words

matter solid liquid gas texture weight magnetic buoyancy float sink strength hardness flexibility transparency transparent translucent opaque absorbency

Review

1. Which best describes matter? (a) Everything that we can see. (b) Everything that has mass and takes up space. (c) Everything we can feel. 2. True or false. (a) Solid matter has a shape of its own. (b) Liquid matter has a shape of its own. (c) Gases spread out to fill the container they are in. 3. What property tells you how light or heavy an object is? (a) Weight (b) Buoyancy (c) Strength

4. What property tells you if an object floats or sinks? (a) Flexibility (b) Buoyancy (c) Transparency 5. What property tells you how much light can pass through a material? (a) Transparency (b) Weight (c) Hardness

6. What property tells you how much liquid a material can hold? (a) Transparency (b) Strength (c) Absorbency 7. List some properties of each object. (a) (b)

(c) (d)

In the Field

If you love art and science, you might want to be an architect. An architect designs and draws plans for structures like buildings and houses. Architects know a lot about materials and their properties. They need to make sure the materials used to build the structures they design are safe and suitable for their function.

Being an architect can be a very rewarding job. You design the places where people live, work or play. If you were an architect, what would you design?

8

Changes to Matter

How can an object made of a small set of pieces be disassembled and made into a new object?

In this chapter you will ...

• describe ways in which matter can change.

• describe how an object made of a small set of pieces can be disassembled and made into a new object.

• observe, test and describe how heat can change matter.

• list some changes caused by heating or cooling that can be reversed and some changes that cannot be reversed.

Go Online!

Access interactive content relating to this topic on the NGScience website.

ngscience.com

How does matter change when it is heated or cooled?

Changing Matter

How Can We Change Matter?

We can change matter in many ways. You can change a sheet of paper by folding or cutting it to make a new object.

What are some other ways we can change matter?

You can change matter by breaking it into smaller pieces, like cutting a loaf of bread.

You can also change matter by putting smaller pieces together to make a big object, like assembling the parts of a toy.

Try This!

Does the mass of solid matter change when it is cut into pieces? Conduct an investigation to find out.

AB Activity 8.1

Sometimes when we change matter, we can also change it back to its original form. You change matter when you assemble blocks to build a toy house. You can also take apart the toy house, leaving the blocks again.

Other times, matter that is changed cannot be changed back to its original form. When you chop firewood, you cannot change it back into a log. When you make a fruit smoothie, you cannot change the smoothie back into the fruits used to make it.

AB Activity 8.2

What are some other examples where matter is changed and cannot be changed back?

Try This!

Take a piece of scrap paper and change it in a way that it can be changed back. Change the paper again in a way that cannot be changed back.

Putting Together and Taking Apart

Different objects can be made by putting smaller objects together. The new objects can have different characteristics, even though they were made of the same set of pieces.

Think Deeply

Imagine you are a builder about to build a new house. Which part of the house would you build first? Why?

Many bricks can be put together to make the walls of a house.

Think Deeply

Imagine you are a builder about to demolish an old house. Which part of the house would you take down first? Why?

An object such as a house is made of many small pieces. The pieces can be disassembled and made into new objects. The bricks used to build the walls of a house can be disassembled.

The disassembled bricks can be assembled again and made into new objects. They could be used to make a garden path or to build a barbecue pit. The new objects can have different characteristics, even though they were made of the same set of pieces.

AB Activity 8.3

Go Online!

Learn about different materials and their properties on the NGScience website. QuickCode: E1X9

Heat and Matter

Changing Temperature

Temperature is how hot or cold something is. When matter is heated, its temperature increases. When matter is cooled, its temperature decreases. Heating and cooling matter can cause it to change from one state to another.

What change in state occurs when solid matter is heated?

Butter melts when it is heated.

Solid to Liquid

When metal is heated, it changes into a liquid.

When matter is heated, its temperature increases. This can cause matter to change from solid to liquid. This process is called melting. Some matter, like ice, will melt at room temperature. It changes from solid ice to liquid water. Other matter requires more heat to start melting.

Try This!

Plan and conduct an investigation to observe how heating and cooling changes a block of chocolate. Describe the changes you observe.

Liquid to Solid

When matter is cooled, its temperature decreases. This can cause matter to change from liquid to solid. This process is called freezing. Placing water in a freezer decreases its temperature. It changes from liquid water to solid ice.

What causes a wax candle to melt and freeze?

AB Activity 8.4

Reversible Changes

The change from liquid water to solid ice is an example of a reversible change.

When water is cooled, it changes to ice. When ice is heated, it changes to water.

What are some other examples of reversible changes that occur when matter is heated and cooled?

A Closer Look

Liquid to Solid to Gas and Back Again

Ice is water in a solid state. When ice is heated, it melts and becomes liquid water. If water is heated, it also changes state – it evaporates into a gas called water vapor.

What happens when water vapor is cooled?

Go Online!

Visit the NGScience virtual laboratory to watch and learn how matter changes state. QuickCode: F6Y1

When water vapor cools, it changes back into liquid water. This process is called condensation.

When the liquid water is cooled, it will freeze and change to solid ice.

Irreversible Changes

Sometimes when matter is changed by heating or cooling, it cannot be changed back. The change is irreversible.

When you fry a raw egg, you use heat to change the matter. The egg can never be changed back to a raw egg.

Think Deeply

What are some irreversible changes that occur when you prepare and eat your breakfast, lunch and dinner?

Cooking toast makes it hard and crispy. Cooling the toast will not change it back to soft bread. The change is irreversible. Popping popcorn and burning paper and wood are also irreversible changes.

Go Online!

Learn more about reversible and irreversible changes on the NGScience website. QuickCode: J4R5

AB Activities 8.5 – 8.6

Science Words

temperature melting freezing reversible change irreversible change

Review

1. Describe two ways you can change matter. 2. Which process occurs when a liquid changes to a solid? (a) Melting (b) Flowing (c) Freezing 3. Which process occurs when a solid changes to a liquid? (a) Pouring (b) Melting (c) Freezing 4. True or false. (a) Matter can change state when it is heated. (b) Matter can change state when it is cooled. (c) Water changing to ice is a reversible change.

5. Label the changes as ‘reversible’ or ‘irreversible’. (a)

(b)

(c)

(d)

A Closer Look

3D Printing

Imagine being able to print an object just like you can print words and pictures on paper. Well, now you can! A 3D printer heats and cools materials to build objects from a design.

Many 3D printers build objects made of plastic. The plastic is heated to become a liquid. The liquid plastic is applied layer by layer to build the object. As each layer cools, it becomes solid plastic again.

3D printers are used to make many types of objects. They are used to make body parts and organs, replacement parts for cars and airplanes, toys and even food. Engineers often print models of their designs to test them before making the real object. How is this useful?

9Heat and Electricity

What are some sources of heat? How do people use heat?

In this chapter you will ...

• list sources of heat and describe how they are used by people.

• describe how heat moves between objects.

• list the ways people use electricity.

• describe how electricity moves in a circuit.

What are some ways people use electricity?

Go Online!

Access interactive content relating to this topic on the NGScience website.

ngscience.com

What Is Heat?

Heat is a form of energy that makes things feel warm. When you place a glass on cold water in the Sun, it gains heat energy and feels warmer.

When you place a warm glass of water in a refrigerator, it loses heat energy and feels cooler.

What happens to an object when it loses heat energy?

Sources of Heat

A source of heat is something that produces heat.

On Earth, the Sun is our main and most important source of heat. The heat from the Sun warms our whole planet and all of the living and non-living things on it. If there was no heat from the Sun, there would be no life on Earth.

What is the main source of heat on Earth?

Think Deeply

What would the Earth be like if the Sun was further away? What if it was closer?

What are some other sources of heat?

Think Deeply

Touch your palms together and rub your hands back and forth. Notice that your hands get warmer. What type of force produces the heat? There are many other sources of heat. Burning wood, gas and oil are sources of heat. When these things burn, they produce heat.

Many appliances and devices in our homes are sources of heat too.

Ovens, kettles and toasters are sources of heat.

Clothes dryers, irons and hair dryers are sources of heat too.

How is heat used by people? What is the source of heat?

AB Activity 9.1

Engineer It!

In small groups, design and build a solar hot water system. Use a thermometer to test your water heater. Compare the water temperature with other groups.

Using Heat

People use heat in many different ways. The heat from the Sun keeps us warm. We also use the heat from the Sun to dry our clothes.

A solar water heater uses the heat from the Sun to warm water for use around the house.

We use heat in many ways in and around our homes. In the colder months of the year, we often use heaters to warm our homes.

We use heat in barbecues, ovens, and stove tops to cook our food. We heat water to boil food and make hot drinks.

We use heat to dry and iron our clothes.

We use heat to warm water for baths, showers and washing dishes.

AB Activity 9.2

Try This!

Place a glass of water outside. Measure the temperature of the water four times throughout the day. Tell how the temperature of the water changed.

Heat and Temperature

Temperature is a measure of how hot or cold something is. The more heat an object gains, the higher its temperature. We can get a rough indication of temperature by using our sense of touch. To accurately measure temperature, we can use a thermometer. A thermometer is a device that measures temperature in degrees Celsius (oC) or degrees

Fahrenheit (oF).

Heat can travel through solids, liquids and gases. Heat always flows from hot objects to cool objects. As the cool object absorbs the energy from the hot object, it becomes warmer. Heat continues to move in this way until the temperature of both objects is the same. Within an object, heat also moves from hot to cold.

Explain what will happen to the wax and thumb tacks attached to the metal rod.

AB Activities 9.3 – 9.5

Think Deeply

Think about the function of these appliances and the tasks they perform. How were these tasks achieved in the past before electricity was discovered?

Using Electricity

Electricity is very useful to people. Many appliances in our homes and schools need electricity to work. Light bulbs, ovens, refrigerators, washing machines and kettles all use electricity produced in power stations.

Batteries

Some devices, such as mobile phones, flashlights and many watches, get electricity from batteries. Batteries come in different shapes and sizes. Some batteries can be used over and over again. Others must be disposed of once they no longer produce electricity.

AB Activity 9.6 Amazing Fact!

Some electric cars are powered by almost 10,000 small batteries. They are able to travel hundreds of kilometers before the batteries need to be re-charged.

Try This!

Make a poster about how you and your family can save electricity at home. Show your poster to your friends.

Saving Electricity

We waste electricity when it is used by appliances that we are not using. Saving electricity helps to make electricity available to everyone. It also saves money. Here are some simple ways you can save electricity at home and at school: • Turn off lights and open curtains and blinds during the day. • Turn off appliances and heaters when you are not using them. • Use low-energy light bulbs.

AB Activity 9.7

Electrical Safety

Electricity can be dangerous if it is not handled correctly and safely. Always follow these electrical safety tips:

• Do not put too many plugs into one socket or power board.

• Do not put anything inside a socket other than a plug. • Keep water away from electrical sockets and appliances.

• Do not play or run around electrical cables.

• Always use an electrician for any electrical repairs.

AB Activity 9.8

Go Online!

Build and test virtual electric circuits on the NGScience website. QuickCode: M3W9

Simple Circuits

An electric circuit is the path along which electricity moves. In a circuit, the electricity travels from a source, through an appliance or device and back to the source of electricity again. A simple circuit consists of a battery, wires and an appliance such as a light bulb. A switch can also be used to control the flow of electricity.

The appliance in a circuit will only work when there is a complete path along which the electricity can flow. When a switch is in the ‘off’ position or there is a break in the circuit, the circuit is open and the appliance will not work.

When a switch is in the ‘on’ position and there is no break in the circuit, the circuit is closed and the appliance will work.

AB Activities 9.9 – 9.10 Did You Know?

Some materials, such as metal, allow electricity to pass through them easily. They are electrical conductors.

Other materials, such as plastic and wood, do not allow electricity to pass through them easily. They are electrical insulators.

Science Words

heat temperature thermometer electricity battery electric circuit

Review

1. What is the main source of heat on Earth?

2. List two sources of heat.

3. List two ways you use heat at home. 4. What is the temperature shown on each thermometer in degrees Celsius? (a) (b) (c)

5. List two appliances in your home that use electricity produced in power stations. 6. List two devices in your home that use batteries. 7. True or false. (a) You should keep lights on even when not using them. (b) Using low-energy light bulbs can help save electricity. 8. List three things you can do to stay safe from electricity. 9. What is an electric circuit?

10. In which circuit will the light bulb turn on?

Tell how you know.

(a) (b)

(c) (d)

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