r r r r r r r r r
Our Essential Question for this unit:
Homework 1.1:
reader player
Data
Introduction 2 Table of Contents 3 Lab 2.1: Mentos Eruption 4-8 Lecture 1.1: Data 9-14 Worksheets 15-20 Review 21-22
measurement
SI Units unit
symbol
size
Unit Prefixes Prefix
mass volume distance amount brightness current time
kilogram liter meter mole candela ampere Second
kg L m mol cd A s
nano (n) micro (m) milli (m) centi Š kilo k) mega (M) giga (G)
billionth millionth thousandth hundredth thousand million billion
3. Complete the table Unit of measurement Length Mass Temperature density
6. Complete the table. Prefix Symbol
We usually use
Factor
Scientific notation 10-9 10-6 10-3 10-2 103 106 109
But SI units require
Scientific notation
example
Giga mega 1,000 centi 10-3 micro
Microgram n m
•
•
• •
• • •
m
•
•
• • • •
Summary 10 points if you summarize your results using numbers to provide details. L1 and honors students- this is a good place to include your mathematical formula that states what you discovered. Be sure to explain the formula so that a stranger could understand it.
Introduction This is where you describe the mentos eruption in general, and then explain what is known about your particular topic. All of your statements should be supported with references. The references need to be reliable, which means either the Coffey paper, or the Guilford Journal of Chemistry. No websites should be used as references. The citations look like this1 and the reference itself is at the end of the paper.
Experimental Procedure This is where you provide a detailed, listed procedure that is repeatable by a stranger. Use numbers so the scale of your experiment is clear. Emphasize safety.
Results For full credit, describe your results, and show them using a table and a graph.
Conclusion This is perhaps the most important part, where you analyze your results and compare them to previous research. What can you safely conclude? How fuzzy is your data- is it tight and repeatable, or does it vary a lot with each trial? For L1 and honors students, this is where you show how your data fits a mathematical formula. Use that formula to predict what could happen if you were to extend your data out beyond your limits‌like using a 4 liter bottle, for example. For full credit, try to explain the reasons for your results. What is it about hot soda that makes the eruption go higher, for example. As we did in unit 1, try to answer on a molecular level. Also, suggest follow up experiments.
References This is a list of peer reviewed books and journals that you are using to support your research. No websites may be used. The numbers correspond to the superscripts in the paper. In the end it should look something like this:
1. Kaitlyn Earles and Megan Graham, Guilford Journal of Chemistry, Volume 2, Pages 21-22 (2008). 2. Tonya Coffey, American Journal of Physics, Volume 76, number 6, pages 551-337 (2008). 3. Nick Hill and Kyle Gaboury, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). 4. Read page 553 of Coffey's paper (see reference 2) for a detailed analysis of the effect of pH on the height of a mentos eruption. 5. Ryan Johnson and Will Graziano, Guilford Journal of Chemistry, Volume 2, Pages 9-11 (2008). 6. Alex Jagielski and Eric Hedberg, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). For full credit include a minimum of 5 useful references formatted like the ones above.
unit 3
How do we find out what everything is made out of?
Unit 3
What is a tomato, mustard leaf, and a strawberry made out of?
L
ook around you. What do you see? In front of you
are all kinds of stuff- all sorts of matter. Some of this matter you can see, and there’s more that you can’t. Some substances, such as those in your body, are undergoing transformations as we speak. And most of it is all mixed together, which complicates things further. What’s it all made out of? It’s a big mess. What we need to make sense of it is a way to sort things out. Our primary goal for this unit is to classify the matter that is all around us. First, we’ll consider what we can say about mixtures. As you might guess, not very much…it varies from sample to sample. So, we will explore some purification techniques. We will spend the remainder of our time finding out what we can about pure substances- these are the materials that the universe as we know it is made from. And since nearly all understanding of matter begins with pure substances, purification is the first step in chemical research. Here’s the plan: Lesson 1: Separation Lab Lesson 2: Leaf Lab Lesson 3 Matter Lecture Lesson 4: Review Lesson 5: Matter test.
A Liquid Chromatograph-Mass Spectrometer (LCMS) can take a complex mixture, separate it, and identify each substance. Shown above are the major components of a tomato (a), mustard leaf (b), and a strawberry (c), with some individual substances (d-f) shown below based on their mass spectrum. Learn more by clicking on the image.
40
Table of contents
Separation Lab Some separation methods to consider
Chemists typically spend more than half of their time purifying substances- separating them into their individual pure components. As a chemist it reminded me of cleaning up a mess at home. In this lab you will be given a mixture of 5 solid ingredients. Typically, these are sand, sugar, salt, iron filings, corn kernels, and pebbles. This year, they are: 1: __________ 2: __________ 3: __________ 4: __________ 5: __________ 6: __________
Separatory funnel
filtration
Your goal is to separate all ingredients of your mixture quantitatively, and analyze your results. You will be graded based on your choice of methods, your report, and percent error: how close your amounts are to the actual amounts provided.
forceps
evaporation
decant
boiling
Homework: Discuss this with your partner and come up with a plan. Write it as a diagram on the next page. You are welcome to use any equipment in the lab as long as you work safely and have it approved by me. Be ready to begin your experiment the following day. You will be allowed to dry any wet samples overnight.
Note that no student has yet come up with a quantitative method to separate salt from sugar.
chromatography
Invent your own
Sample Separation Scheme pebbles Iron filings Method salt sugar sand
sand Iron filings pebbles
pebbles
Iron filings Method salt sugar
salt
Method Iron filings
Iron filings salt sugar
salt Method sugar
Most common errors: -No separation or only partial separation of salt and sugar. -Samples still wet after overnight drying.
Separation lab (continued) Homework: Draw a neat diagram outlining your separation procedure, using the scheme shown on the following page. Note that you will have 60 minutes of class time only over two days to complete your separations.
Sand is an ingredient, but is not actually pure, as it contains hundreds of substances in addition to quartz (SiO2)
Once you have the stamp of approval, begin your separations. Time your work so that any sample drying takes place overnight. When you are done place each sample in a labeled plastic bag, and ieach ndividual bag in a final plastic bag- your instructor will model it for you. You will be graded based on the purity and amount of each sample. Fill in the data table and complete the Analysis section below.
Separation Lab: Data Mass of mixture
________ g
Mass of component 1 (__________)
________ g
Mass of component 2 (__________)
________ g
Mass of component 3 (__________)
________ g
Mass of component 4 (__________)
________ g
Precision: 1 point off for each percent error
_____ /10
Mass of component 5 (__________)
________ g
______ 10
Mass of component 6 (__________)
________ g
Sample Purity (by inspection)
Total mass of separated components
_______ g
Neatness and accuracy of report and analysis
_____ /10
Total
_____ /30
Percent Error
________ %
Your Score
Analysis: Write a paragraph summarizing your experiment, and reflect on the results. Be sure to include recommended improvements if you were to repeat the process. Use additional paper if necessary.
Lab 3.2 The matter all around us is rarely in a pure form; most of what is around us are mixtures. Perhaps the most complex mixtures are those in living things. To understand what is in a mixture we must separate the individual substances contained in a mixture. In our very first experiment you each planted a seed and by now you should have several leaves. The goal of this experiment is to isolate some pure substances from that leaf. If you have need to, bring in some fall leaves from home. Every leaf contains thousands of individual chemicals. We’ll focus on three visible groups with characteristic fall colors: the carotenes, xanthophylls, and chlorophylls. Their chemical structures and typical colors are shown on the right
1. 2.
Which is more greasy (“hydrophobic”): the carotenes or the xanthophylls? Which is more greasy: chlorophyll A or B? Why?
Background: Chromatography (“color writing”) is a powerful tool for purifying mixtures. We will use paper chromatography to isolate the visible substances in a leaf. To do this we will make a thin paste of leaf goo using a powerful solvent (methanol), then paint it on chromatography paper, which is our “stationary phase. We then place it in a jar that has some organic solvent on the bottom (our “mobile phase”, and allow the solvent to move up the paper, separating the mixture based on the adherence to the paper, and the solubility in the solvent. Your task is to find a solvent system that will separate the mixture. Watery solvents such as methanol or acetone tend to dissolve everything and move the mixture rapidly. Greasy solvents such as hexane don’t tend to move the mixture much at all. Try a few combinations until you get nice separation, like the chromatogram shown below. Not the identity of each band, and how the distance traveled by the substance is measured using Rf value, where all the way up to the solvent front has a value of 1, and the baseline has a value of zero.
Carotenes
Rf = 1.0
Xanthophylls Rf 0.37 mystery substance Rf 0.32 Chlorophyll A Rf 0.21 Chlorophyll B Rf 0.16
Carotenes: Gold to Orange
Xanthophylls: Light Yellow
Chlorophyll A: Forest Green
Chlorophyll B: Olive Green
Using the techniques described in this lab report and demonstrated by your instructor, find a solvent system that provides optimum separation of visible leaf constituents.
Tape your chromatogram here. Identify each band and measure its Rf value.
Tape your best chromatogram to this lab report and measure the Rf value of each visible substance. Note that your values do not have to match those on the previous page.
Tape your best chromatogram to this lab report and measure the Rf value of each visible substance. Note that your values do not have to match those on the previous page.
Score: Prelab questions: _____/3 Separation: _____/3 Identification: ____/3 Rf measurements: _____/3 Total: ___/12
Solvent system used: _____% ____ _____% ____
Matter Unit 3
Our essential question: How do we find out what everything is made out of? A good place to start: Classify it.
Matter Element, molecule, or mixture?
gold element
ocean mixture
milk mixture
copper glass element
molecule
Think of an example of each. Element:
Molecule:
Mixture:
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
Nothing is pure in this world. What can we say about mixtures?
Looks pure but isn’t
doesn’t look pure
One thing visible
Multiple things visible
homogeneous “a solution”
heterogeneous “a mixture”
Either way it’s still a mixture… until it is separated we don’t know much about it.
Solutions: solid-liquid: Salt water solid-solid: brass;steel
Gas-gas:
air
Gas-liquid: soda liquid-liquid: Gasoline; vinegar
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
• Purification: How to separate mixtures.
• You have
• want • sand • sugar • oil: • oils pure: • Technique:
• decant • filter
• All.
• crystallize
• distill • chromatograph
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
Physical vs. Chemical Properties of Matter Stays the same
New substance(s) formed
Chemical Properties include
flammability
rust
ductility
Physical Properties include:
Melting point
color
density
Boiling point
magnetism
crystallinity
malleability
Refractive index
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
luster
Extensive and Intensive Properties • amount-dependent
Doesn’t matter how much
• ”extent”
ex
in mass
Melting point
ex
density
in
Refractive index
toxicity
in
crystalline
amorphous
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
Phase Changes
hot
gas condense
boil
deposit
sublime
liquid melt
freeze cold solid
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
5 states of matter hot
Assumes Fills Shape of Container? Compressible? Container?
State?
plasma
cold
no
no
??
gas
Yes
yes
yes
liquid
Yes
no
no
Liquid crystal
YesBut ordered
no
no
solid
no
no
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
no
Liquid crystals and plasmas Ordered liquids
charged gases
Nematic liquid crystal:
Linear alignment Smectic liquid crystal:
Planar alignment
L2: End matter ď Š
Coming next: the atom
1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals
Modern Separation Methods (L1, honors only) Still in Use
Layer separation
distillation
Paper chromatography
filtration
crystallization
Vacuum distillation
Thin layer chromatography
Spinning band distillation
Gas chromatography
High performance liquid chromatography (HPLC)
Classical Identification Methods (L1, honors only) Still in use
Melting point
Boiling point
Modern Identification Methods (L1, honors only
Flame ionization
Nuclear magnetic resonance spectroscopy (NMR)
All-in-one LCMS
Infrared spectoscopy
Mass spectrometry
Classifying Matter
ws 3.1
What is everything made out of? Our essential question for this course: To say that the universe is made out of matter is true, but doesn’t provide much detail. It would help to classify mater.. Let’s start with elements. The universe as we know it has about 100 elements. Occasionally we see them in their isolated form- for example an engagement ring may be pure gold (Au), with a diamond on it, which is pure carbon (C ).
More often we see the elements bonded together to form molecules, such as water (H2O) or table salt (NaCl). Sometimes called compounds,* molecules are made out of multiple elements which are bonded together and they have constant physical properties. For example, water freezes at 0 oC, and table salt melts at about 2000 oC.
What is everything made out of?
If we look closely at the things around us, we find that most of them are mixtures of molecules. Drinking water, for example, is mostly made out molecules of water, but also has some molecules of salts (like NaCl) and may have be fluoridated as well. Classify each of the materials below as an element, molecule, or mixture. The examples below should help get you started. It’s OK if you miss a few…this is to get us thinking about what things are made out of. A key will be passed out after you complete this. Element, molecule, or mixture?
What is a diamond ring made out of?
A. Silver Answer: Silver is an element (Ag). B. Air Answer: air is a mixture of nitrogen (an element), oxygen (an element), and, among other things, carbon dioxide (a molecule). C. Ice Answer: ice the solid form of water, which is a molecule (H2O).
Classify the 19 materials on the next page, then check the answer key to see how you did.
*You
should be aware that many texts differentiate between molecules and compounds. In this class we won’t go there. If you’d like to see the confusion that it can lead to, click here or here.
Element, molecule, or mixture?
Material A. Silver B. Air C. ice 1. Mud 2. sugar 3. steam 4. Baking soda 5. Alumninum foil 6.brass 7. blood 8. Bubble gum 9. gatorade 10. chalk 11. glass 12. Soy sauce 13. grasshopper 14. gasoline 15. urine 16. snow 17. milk 18. tobacco 19. Pencil lead (graphite)
Element ?
Molecule?
Mixture?
20. Look around you. Try to find examples of elements, molecules, and mixtures in front of you right now. 1. An element in front of me:______ 2. A molecule in front of m:________ 3. A mixture in front of me:________ 21 (L1, honors only) Use the following 6 definitions to make a classification chart similar to the one at the end of unit 1. A sample to get you started is at the bottom right of page 18. Matter: Anything with mass and space. Element: A substance with a fixed number of protons Molecule: Atoms bonded together Compound: Different atoms bonded together Mixture: More than one substance Substance: A pure form of matter each of the 7 words below on your chart as examples. Consider if some should go in more than one place.. Also ask yourself if pure elements are bonded together. Oxygen (O2) Water Iron Carbon Diamond Graphite Sodium chloride
Humans love to classify everything.
Matter classification chart (L1, honors only)
ws3.3
A walk on the beach
Introduction to Matter Summary Worksheet
Crystalline Amorphous Matter Substance Compound Solid Gas Heterogeneous
Homogeneous Liquid crystal Liquid Sublimation Deposition Boiling Melting Condensation
Chemical Physical Silicon Oxygen Ozone Precise accurate
While walking down the beach one day, I spied a small object. I noticed it has both mass and took up space, so I was sure it was ___________. I picked it up and took a look at it under a magnifying glass. I could not see any impurities in this glassy object, therefore I was pretty sure it was _____________________. I assumed it was pure, so I classified it as a ____________________. I took it home and heated it over a fire, but it did not melt, so I can’t really say anything about that __________________(physical, chemical) property. I hammered it and it did not flatten; it is not _____________. I tried to stretch it and could not; it is not _______________. This material is a colorless solid. By the way, The other states of matter are ___________, _____________, and _____________. A few believe that _____________ represent a fifth state of matter, and this phase could either be in a ____________ or _____________ state. My little rock is just a simple solid. Since it is shiny I could say it is ___________. If I had the right equipment I could heat it up to a liquid (_________ it), or perhaps even heat it further from a liquid to a gas (_______________). It’s possible that when I heat it up it might go directly to a gas (_______________), but I doubt it. I do know that iodine vapors can cool directly to form a solid (_______________), but that has nothing to do with my story. I happened to have some hydrofluoric acid kicking around, and when I dropped in my substance to that nasty acid, it dissolved. That _____________(physical, chemical) change was weird. I sent it out to an analysis lab and they told me that my 600 milligram sample consisted of 280 milligrams of Si (_______________), and the rest was O (_______________). The percent composition of my sample is therefore _______% Si, and ________% O. And I thought my substance was a pure element, but really it is a just a _________. I submitted several similar samples I found at the beach and they all gave exactly the same analysis; this data is very ___________. I assume the people at the lab know what they are doing so it is probably __________ as well. L1 and honors students know that if I could prepare a solution of my substance I could puriy it and have the minor impurities identified using a single machine known as a ___________. But I’m pretty sure I know what it is already. My substance is______________.
ws3.4
I need it Pure
Modern Purification and identification methods worksheet After listening to the matter slideshow, especially the last two slides on modern methods of sample purification and identification, answer the questions below using some but not all of the words below
Place an I in front of each term above that refers to compound Identification, and a p in front of methods used for Purification 1. Which method is best for separating oil from water? __________________________ 2. Which method is best for separating two liquids whose boiling points only differ by one degree Celsius? ________________ 3. Which method is appropriate to separate 5 mg of a solid organic substance? _______________ 4, I’d like the elemental composition of a pure metal. A good method would be______________ 5. I’d like to separate a separate a sample of Martian Air into it’s individual components…a good choice would be:______________________________ 6. This method of sample identification is used for organic compounds, and although it provides a nice “fingerprint of the substance, has been largely replaced by more informative methods such as___________ 7. This method of sample identification creates predictable peaks based on the composition of the elements next to the point in question._________________________ 8. This method of sample identification produces a molecular ion which is a good measure of the molecular weight of the substance._______________________________________ 9. This is an old method of purification still in use, gives incredible sample purity, and was used in the rock candy experiment __________________________________ 10. This will do for separating oil and water __________________________________ 11. For the separation of complex mixtures which can be dissolved in a solvent, this method is hard to beat._________________________________________ 12. Used in the leaf lab, this method will separate a crude sample into many individual substances but is rarely used professionally. ____________________________ 13. This is the ultimate solution: it will separate and identify just about any solution, no matter how complex.___________________________________
How to ace the Matter test
Howtoaceitunit3
In this our third unit we learned how to purify and classify matter. Matter in its natural state is a mixture of substances, and to study them we purify and identify them, and determine their properties. The mixtures may look pure (homogeneous) or many things may be visible (heterogeneous). The pure substances occasionally are composed of only one element, but more often are molecules that consist of multiple elements bonded together. There are a nearly infinite number of individual substances on earth, and chemists have learned how to mak evirtually any new substances (though not always very quickly) of their own design.
We have seen how substances may be classified based on how their atoms are arranged (for example functional groups such as aldehydes, ketones, etc.). They may also be grouped into their 5 physical states, their physical, or their chemical properties. A chemist spends the majority of his or her time purifying mixtures, and we spent some time doing that. We used basic techniques such as decanting, filtration, distillation, and chromatography to isolate some pure substances from a mixture. L1 and honors students explored the modern equipment used for separations including high performance liquid chromatographs and spinning band distillation devices. All students learned basic methods to identify pure substances such as odor, melting point, and conversion to known compounds. L1 and honors students also learned about modern spectroscopic methods to identify substances such as nuclear magnetic resonance (NMR) spectrometers. Finally, they had a glimpse at the future with some state of the art devices that can purify a mixture and identify each substance in it such as a LC-MS (liquid chromatograph-mass spectrometer). To ace this test be sure to understand the packet, including all lab experiments, slides, and worksheets. Go online and watch the screencasts of the slides if necessary. Be ready to separate a mixture if given one. Take a brief look at the first two units, since they are fair game on a test. Review your notes from your lab notebook, including all demonstrations and chalk talks. Finally consider the significance of the long term experiments we have been monitoring- the rock candy lab, and the seed lab. In our next unit we will zoom in enormously from our macroscopic view of matter and will ask ourselves what the smallest building blocks of matter are- this is the atom unit coming up next. Be able to provide detailed answers to the questions below. Have a thorough understanding of the concepts below. Be able and ready to separate a mixture if given one.
1. What is matter? Matter is_____________________
14. How to separate mixtures a. Sugar from sand
2. What is a substance? A substance is a __________ _________ or ____________
b. Iron from sand
3. What is a physical property?
d. Blue ink from black ink
c. Water from the ocean
4. What is a chemical property?
15. What is an element?
5. How could I separate sand from aluminum powder?
16. What is a compound?
6. What are the 5 states of matter? 7. Where can I observe plasma? 8. What are liquid crystals? 9. What are the two types of liquid crystals and how do they differ?
17. Why is chromatography such a powerful method for the separation of chemical mixtures? 18. Draw a chromatogram of a sample that has a Rf of 0.75 19. What does HONC mean? 20. Draw propanol, C3H8O using both a structural and skeletal formula.
10. Describe the six conversions of matter states (boiling, melting‌)
11. What is the law of conservation of mass? 21. Draw two isomers of butane, C4H10, 12. Define malleable and ductile and give examples of each. 13. Heterogeneous mixture = ___________________; homogeneous mixture =___________________ Homogeneous mixtures can be solid/liquid (______________), liquid/liquid (______________), gas/liquid (______________), gas/gas (______________), or even solid/solid (______________).
22. To put this unit in perspective, modify the conceptual diagram at the end of unit 1 to include the main concepts of the matter unit.
22. What is an atom? This is our next unit.
urushiol
Toxicodendrons radicans (poison ivy)
Poison Ivy (Toxicodendron radicans, shown at left) produces the urushiol class of allergens, including the one shown
The Atom Unit 4
How do we know that the world is made out of atoms? A historical approach. Page 69 Unit 4: the atom
Unit 4: the atom
Unit 4: the atom
Mikhailovsk ij field emission electron microscopy (FEEM) Atomic image Rutherford including 1790 orbitals jimmy neutron
Democritus Atomos Evidence: nothing
Aristotle Earth, Air, Fire, Water: Phases!
Ghazali Alchemist We can split the atom
Thomson Electrons Plum pudding Dalton: bonds Atoms combine in small whole numbers
Lavoisier Balance: Indestructible Conservation of mass
• • • •
• •
• • •
History of the atom worksheet
ws 4.1
Complete this worksheet after listening to the presentation on the history of the atom from 400 BC to 1907 AD. Refer to the notes on your slides if you need to for each question. 1. What is the essential question for this course? 2. What is the essential question for this unit? 3. What would you need to see, know, or observe to become convinced that atoms exist?
4. By now you have seen a presentation on some ideas and experiments concerning the atom from about 2400 BC to 1907. Fill in the table below to summarize the work and significance of some of the key players. name
Democritus
Aristotle
Ghazali
Lavoisier
Dalton
Thomson
Rutherford
Symbol
Contribution
5. How is Daltons model of the atom different from that of Democritus?
6. Draw a picture of the Cathode Ray tube used by Thomson, identifying each component. Show 2 experiments that indicate the green light in the tube is in fact not light.
7. Light is a form of electromagnetic energy and has no mass. Compare that to the green light in the cathode ray tube.
8. How might the gold foil experiment suggest the shape of an atom?
9. How big is an electron compared to a hydrogen atom?
10. Draw a figure and explain Rutherford’s Gold foil experiment:
11. Lavoisier’s experiments indicated that mass is never lost when chemical reactions occur. Daltons experiments suggested that elements come in different sizes, and they combine in simple ratios. Thomson showed there is something smaller than hydrogen, and Rutherford showed that there is a lot of empty space in matter. Based on those experiments and a hunch that the atom may resemble our solar system, the early 20th century model of the atom is the Jimmy Neutron symbol. To understand the atom is to understand all matter on its most basic level. What did they still NOT know about the atom at this point? List as many things as you can.
Atomic Bookkeeping Worksheet
ws 4.2
Atomic Particles, Atomic Number, Mass Number, Ions, and Isotopes Here are some quick facts to help you keep track of the names and numbers associated with the atom:
Protons are in the nucleus, each has a +1 charge, and identifies the element. Neutrons are in the nucleus, each has no charge, and determines the isotope. Electrons are outside the nucleus, each has a -1 charge, and determines the reactivity. Atomic Number is the number of protons. Mass number is the number of protons + neutrons Average atomic mass is the averaged mass for a mixture of isotopes An ion has either more or less electrons than protons, so it is charged. Isotopes vary only in the number of neutrons for an element. 1. Pick an element, any element. My element has the symbol _______, which stands for ____________. It has ______ protons, and when uncharged also has _________ electrons. The average atomic mass of this element is ________ atomic mass units. If it has one extra electron, this would give it a _____ charge. If one atom had two more neutrons than protons, the mass number would be ________ atomic mass units. 2. Fill in the blanks below: ____________average atomic mass ____________chemical symbol ____________chemical name ____________atomic number
Hydrogen 1 H 1.008
3. Complete the following table: Element O (oxygen) Zn (zinc)3+ Sn (tin)Fe (iron)3+ C (carbon) H (hydrogen)+ Sg (seaborgium)
Number of protons 8
Number of electrons
4 What is an isotope? 5. What is the difference between mass number and atomic number?
Average atomic mass 15.999
1. Complete the following table:
Atomic mass/average atomic mass worksheet Element O (oxygen) Zn (zinc) Sn (tin) Fe (iron) C (carbon) H-(hydride) Note the negative sign! Sg (seaborgium)
Number of protons 8
Number of electrons 8
Number of neutrons 9 37
Mass number 17 118
30 14 0
266
2. Mass number and atomic number are easy to confuse. To determine atomic number one only needs to know the number of _____________, whereas the mass number also includes the number of_____________. 3. Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37. The lighter isotope is _____ which contains _____ protons and _____ neutrons. The heavier isotope is _______ with _____ protons and _____ neutrons. 4. Here is a problem that is solved for you. As you read the problem, imagine how you could solve it without a calculator, then see how it is done, and apply the solution to #5. An imaginary element X has two isotopes, one with a mass of 20 atomic mass units (amu), and the other with a mass of 22 amu. They both occur with equal (50%) abundance. What is the average atomic mass of X? Solution: (0.5)(20) + (0.5)(22) = 21 a.m.u. 5. What would the atomic mass of element X above be if the abundances of X-20 was 25%, and the abundance of X-22 was 75%? Solution (fill in the missing numbers: ( )( ) +( )( ) = _____ a.m.u. 6. Silver has 2 isotopes. One has a mass of 106.905 amu (52%) and the other has a mass of 108.905 amu (48%). What is the average atomic mass of this isotopic mixture of silver?
Isotopes, ions, atomic mass, and average atomic mass worksheet
ws4.3
The number of protons, electrons, and neutrons is usually symbolized in an element box in the following manner: For example: 235 41 Mass number 19 2+ (p + + n 0)
24
Charge (p + + e -)
9
Na+
F-
Ca
20
U
92
11
9 protons 10 neutrons 10 electrons
atomic number (p + )
20 protons 21 neutrons 18 electrons
92 protons 143 neutrons 92 electrons
Once the number of each atomic particle is known, it is an easy matter to identify isotopes (atoms that vary only in the number of neutrons) or ions (atoms that do not have the same number of protons and electrons). 1. Fill in the blanks
34
35
16
17
S
___protons ___ neutrons ___electrons
Cl
-
238
6+
U
92
___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons
32
35
238
16
17
92
S
Cl
4+
U
___protons ___ neutrons ___electrons
___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons
7 protons 9 neutrons 8 electrons
8 protons 105 protons 132 neutrons 8 neutrons 106 electrons 8electrons
2. Which pairs of elements are isotopes?
3. Which elements are ions? 4. Fill in the boxes below.
1 protons 0 neutrons 1 electron
23 protons 24 neutrons 22 electrons
5 protons 6 neutrons 8 electrons
5. Are the following pairs of compounds isotopes, ions, or different elements? Also, provide the full atomic symbol for each substance Example: a. Substance 1: 10 protons, 10 neutrons, 10 electrons: b. substance 1: 10 protons, 11 neutrons, 10 electrons Relationship: isotopes
21
Ne
10
c. Substance 1: 10 protons, 10 neutrons, 10 electrons d. substance 1: 9 protons, 10 neutrons, 10 electrons Relationship:________________ e. Substance 1: 10 protons, 10 neutrons, 11 electrons f. substance 1: 10 protons, 10 neutrons, 10 electrons Relationship:________________ 6. Determine the average atomic mass for the following imaginary elements, using the first question as an example.
Solved Example. Isotope 1: 4 protons, 4 neutrons. Abundance : 91% Isotope 2: 4 protons, 5 neutrons. Abundance : 9% Average atomic mass = sum of (abundances)(mass number) = (0.91)(8 amu) + (0.09)(9 amu) = 8.09 amu a. Isotope 1: 14 protons, 14 neutrons. Abundance: 62% Isotope 2: 14 protons, 16 neutrons. Abundance : 38% Average atomic mass =
b. isotope 1: 94 protons,104 neutrons. Abundance : 52% Isotope 2: 94 protons, 112 neutrons. Abundance: 48% Average atomic mass =
c. Isotope 1: 24 protons, 24 neutrons. Abundance : 40% Isotope 2: 24 protons, 25 neutrons. Abundance : 39% Isotope 3 : 24 protons, 28 neutrons abundance = 21%
3. Level One Only: Boron has two naturally occurring isotopes. Boron -10 (abundance = 19.8%; mass = 10.013 amu) and another isotope (abundance 80.2%). The average atomic mass of boron is 10.811 amu. What is the mass of the other isotope?
How to ace the Atom unit
Howtoaceitunit4
In this our fourth unit, we explored the atom. Our goal was to answer the question: How do we know that atoms exist? We began with a chronological study, starting with the ideas of Democritus, and ending with the discovery of the nucleus by Rutherford. We also considered what it would take to convince us that atoms in fact do exist, and we found evidence that atoms have been individually observed and moved. We then focused on the three primary subatomic particles. We considered their location, mass and charge, and this led to an understanding of atomic number, mass number, and average atomic mass. Finally, we applied this to isotopes, and finished with the band of stability- the ratio of protons to neutrons for a stable atomic nucleus. In our next unit we will focus on the subatomic particle that determines the chemical behavior of each element: the electron. To ace this unit you should review the powerpoint slides, the atom worksheets, and this study guide. You should also review the results of our Seeing the Atom project. Here are some quick questions on each topic we covered. 1. The history of the discovery of the atom: a. Aristotle and his four “elements� b. Democritus: symbol and what he got right c. Paracelsus: Symbol and contribution d. Lavoisier: Symbol, contribution, and his untimely end e. Dalton: symbol and his major contribution f. Thomson: symbol, what he discovered, device he used, evidence . g. Rutherford: symbol, and his key experiment 2. The 3 subatomic particles, their mass in atomic mass units (amu), and charges
3. Atomic number
Example: What are the atomic numbers for each element in baking soda, NaHCO3? Why can Magnesium never have 13 protons?
4. Mass number
Example: What is the mass number of an oxygen atom that has 8 neutrons and 9 protons?
5. Average atomic mass formula
Example: Element X has two isotopes. One has an abundance of 63% and an atomic mass of 10 a.m.u. The other has an abundance of 37% and an atomic mass of 15 a.m.u. What is the average atomic mass of element X?
6. Isotopes- definition (watch out for cases that are different elements, not different isotopes)
Example: How many protons and neutrons are present in an atom of Cs-111?
7. Ions- know how to calculate charge on an atom
Example: How many protons, neutrons, and electrons are present in an atom of C-13?
Example: Draw element boxes that show an example of a fluoride monoanion (-1), and a calcium dication (+2).
8. Nuclear stability
Example: Circle the stable isotopes: U-238 Po-208 C-14 9. Chemical symbols for elements 1-20
What are the symbols for
hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, argon, potassium, and calcium,? 10. How do you know that atoms exist? Provide quantitative evidence in addition to imaging. Be sure to review the Seeing the Atom Presentations from each of you. Good luck on the test.
How to ace the Atom unit KEY
Howtoaceitunit4
In this our fourth unit, we explored the atom. Our goal was to answer the question: How do we know that atoms exist? We began with a chronological study, starting with the ideas of Democritus, and ending with the discovery of the nucleus by Rutherford. We also considered what it would take to convince us that atoms in fact do exist, and we found evidence that atoms have been individually observed and moved. We then focused on the three primary subatomic particles. We considered their location, mass and charge, and this led to an understanding of atomic number, mass number, and average atomic mass. Finally, we applied this to isotopes, and finished with the band of stability- the ratio of protons to neutrons for a stable atomic nucleus. In our next unit we will focus on the subatomic particle that determines the chemical behavior of each element: the electron. To ace this unit you should review the powerpoint slides, the atom worksheets, and this study guide. You should also review the results of our Seeing the Atom project. Here are some quick questions on each topic we covered. 1. The history of the discovery of the atom: a. Aristotle and his four “elements” cross, AFEW b. Democritus: symbol and what he got right Ball; the world is made out of atoms c. Ghazali: Symbol and contribution split ball; suggested we could split the atom d. Lavoisier: Symbol, contribution, and his untimely end balance; atoms may be indestructible; guillotined e. Dalton: symbol and his major contribution barrel o’monkeys; bonds f. Thomson: symbol, what he discovered, device he used, evidence .plum pudding; electrons; cathode ray tube; magnet, propeller, and mass to charge ratio g. Rutherford: symbol, and his key experiment james Isaac neutron; gold foil 2. The 3 subatomic particles, their charges P+, N0, E3. Atomic number
Example: What are the atomic numbers for each element in baking soda, NaHCO3? Na 11, H1, C6, O8 Why can Magnesium never have 13 protons? Yo that’s aluminum bro
4. Mass number
Example: What is the mass number of an oxygen atom that has 8 neutrons and 9 protons?
17 5. Average atomic mass formula
Example: Element X has two isotopes. One has an abundance of 63% and an atomic mass of 10 a.m.u. The other has an abundance of 37% and an atomic mass of 15 a.m.u. What is the average atomic mass of element X? We estimate‌most of it is 10, some of it is 15‌about 12
6. Isotopes- definition (watch out for cases that are different elements, not different isotopes)
Example: How many protons and neutrons are present in an atom of Cs-111?
55P,, 56N 7. Ions- know how to calculate charge on an atom
Example: How many protons, neutrons, and electrons are present in an atom of C-13? 6P, 7N, 6e Example: Draw element boxes that show an example of a fluoride monoanion (-1), and a calcium dication (+2). Heres the list: F- has 9P, 10e, average atomic mass of 18.9 amu Ca +2 has 20 P, 18 e, and an average atomic mass of 40.0 amu
8. Nuclear stability
Example: Circle the stable isotopes: U-238 Po-208 C-14 9. Chemical symbols for elements 1-20
What are the symbols for Refer to periodic table hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, argon, potassium, and calcium,?
10. How do you know that atoms exist? Provide quantitative evidence in addition to imaging. Please be prepared to write a persuasive essay. Be sure to review the Seeing the Atom Presentations from each of you. Good luck on the test.
Unit 4: the atom
How do we know that the world is made out of atoms? List 2 types of evidence that would convince you personally that atoms do in fact exist: 1. 2. Democritus 400 BC ball Mikhailovsk ij 2009 picture
Aristotle 350 BC cross
Rutherford 1790 jimmy neutron Thomson 1905 plum pudding
Ghazali 1100 split ball
Dalton 1820 earrings
Lavoisier 1790 balance
Within the framework of this approximation, the compres-sion factor is given by f = (r0/L)1/2, (1)
where L is the total distance of the apex of the hemisphere from the paraboloid surface (L=l+p0) and is a numerical constant which is almost independent of configurations of chains and supporting tips and has an approximate value of 1.145.17 The apex field-enhancement factor for the chain on a paraboloid model is given by -=1.05(2+L/p0)0.99. The field F at the end of the chain anchored at the apex of a parabo-loidal tip can be shown to be F=2-V/r0 ln(2R/r0). Using these expressions, the calculation yielded the following ex-pression for the minimal diameter of resolved emission spots in FEEM images of free-standing linear nanoobjects: −1/4 eme 1/2 0 = (21 p0) [-LF ln(2R/r0)]. (2)
Imaging the atomic orbitals of carbon atomic chains with field-emission electron microscopy I. M. Mikhailovskij,* E. V. Sadanov, T. I. Mazilova, V. A. Ksenofontov, and O. A. Velicodnaja Department of Low Temperatures and Condensed State, National Scientific Center, Kharkov Institute for Physics and Technology, Academicheskaja, 1, Kharkov 61108, Ukraine (Received 17 July 2009; revised manuscript received 2 September 2009; published 7 October 2009) A recently developed high-field technique of atomic chains preparation has made it possible to attain the ultrahigh resolution of field-emission electron microscopy (FEEM), which can be used to direct imaging the intraatomic electronic structure. By applying cryogenic FEEM, we are able to resolve the spatial configuration of atomic orbitals, which correspond to quantized states of the end atom in free-standing carbon atomic chains. Knowledge of the intra-atomic structure will make it possible to visualize generic aspects of quantum mechanics and also lead to approaches for a wide range of nanotechnological applications. DOI: 10.1103/PhysRevB.80.165404 PACS number(s): 61.05.-a, 68.37.Vj, 81.07.Vb
Mikhailovsk ij field emission electron microscopy (FEEM) Atomic image Rutherford including 1790 orbitals jimmy neutron
Democritus Atomos Evidence: nothing
Aristotle Earth, Air, Fire, Water: Phases!
Ghazali Alchemist We can split the atom
Thomson Electrons Plum pudding Dalton: bonds Atoms combine in small whole numbers
Lavoisier Balance: Indestructible Conservation of mass
Unit 4: the atom
w
1 1 1 0.01097 2 2 2 n
Names___________________________________________Period______________ lab5.1 Flame Tests Lab 20 points Safety Notice: This lab is exciting, but please be cautious. Wear goggles. Assume all salts are toxic, as are all gases produced. Introduction: We have all seen the beautiful colors that can form when substances are placed in a flame. Pockets of gas in wood can form green and blue colors when they ignite. What is happening when this occurs? This answer was the key to unlocking the secrets of the electron, now known as quantum theory. In this experiment we will observe some of these colors, and will make some initial attempts to explain it. Finally, the color of the emitted light will be used to identify the unknown salts. Chart: Wavelength (in nanometers) of visible light
Table 1: Color and wavelength in nanometers of emission spectrum of salts and unknown.
Salt 1. 2. 3. 4. Unknown #_____ Unknown #_____
Flame color
Estimated wavelength (nm)
Analysis 1. Each of the known compounds tested contains chlorine, yet each compound produced a flame of a different color. What does this suggest?
2. We will learn this week that the movement of electrons in atoms produces the colors we observed. What specifically may be going on with the electrons to produce color? (take your best guess)
3 (l1, honors only) .Using the periodic table below, draw the color of light for each cation observed, and look for a pattern.
4.Based on the colored periodic table above, and your best guess as to what may be going on with the electrons, fFind a pattern and describe it in one sentence:
5. Based on this pattern predict the color observed when each salt is exposed to a flame: Calcium chloride______________ Cobalt chloride_______________ Zinc chloride______________
Team Names_________________ and ____________________ Period _____ Lab 5.2
Spectroscopy Lab Introduction: In our previous lab we observed the vivid colors emitted by placing chloride salts in a flame. This was followed by a demonstration where we observed how a spectroscope (a prism, really) can divide up light into separate wavelengths. We now know our eyes can only see a tiny section of the electromagnetic spectrum shown below:
The purpose of this lab is to combine these two observations by repeating the flame test experiment, this time using a spectroscope. This experiment is similar to that performed by Niels Bohr and others, and begs the question: what does it all mean? How do the spectral lines relate to the structure of the atom? Safety: As before, this lab uses flames and toxic salts. Please wear goggles. Procedure: 1. Put on goggles. 2. Each group will perform a 5 minute experiment at each of 6 stations, and then proceed to the next. As precisely as you can, draw the component wavelengths observed at each station. Follow the instructions for each station, clean up, and be ready to move to the next station. Station 1: Sunlight. Each student should point through the spectroscope directly at the sun, and draw the component wavelengths observed. If weather permits, see if the colors are the same when you are not looking through a window. Station 2: Artificial light
Each student should point through the spectroscope directly at the fluorescent lights, and draw the component wavelengths observed: Station 3: Copper Chloride Dip a paper clip into a copper chloride solution, and place it in the flame for less than two seconds while your partner observes the emission of light through the spectroscope. Repeat as necessary, but be cautious not to ignite the splint. Station 4: Magnesium Combustion Request a piece of magnesium metal from your instructor. Holding it in tongs, ignite the magnesium and observe the spectrum through the spectroscope. Warning: The light is extremely bright, and burns at 2000 degrees Celsius. Station 5: Hydrogen gas Turn on the hydrogen gas spectrum tube and observe the component wavelengths through the spectroscope. You should see individual spectral lines. Station 6: ______ Gas Turn on the ________ gas spectrum tube and observe the component wavelengths through the spectroscope. You should see individual spectral lines. Data: Using colored markers, Draw what you see through the spectroscope as accurately and precisely as you can. The marks are at 450, 550, and 650 nm. 400
500
600
700
400
500
600
700
400
500
600
700 700
1. Sunlight 400
500
600
2. Fluorescent Light 700
400
500
600
3. Copper Chloride 700
400
500
600
700 700
4. Magnesium combustion
5. Hydrogen Gas
6._______ _____________ _
Please answer the following questions at your normal seats: 1. Describe what you observed at each station: 1. 2. 3. 4. 5. 6. 2. Which light source provided the simplest spectrum? 3. Which light source provided the most complex or varied spectrum? 4. What were the wavelengths (in nanometers) of the individual lines from hydrogen in nanometers? 5. What were the colors of the individual lines from hydrogen? 6. Now that you have seen a variety of emission spectra, what do you believe causes the “lines”?
7(L1, honors only). Homework assignment: Research this topic, and explain where the observed “lines” from the hydrogen emission spectrum come from. Your explanation should include a diagram, and the application of the Balmer formula.
1 1 1 0.01097 2 4
w
1 1 1 0.01097 2 2 2 n
3Li:
1s2 2s1
6C:
X 1s2 2s2 2p2
1s2 2s2 2p2
Hund’s Rule: Electrons spread out within orbital groups
16S:
1s2 2s2 2p6 3s2 3p4
1s2 2s2 2p2 1s2
1s2 2s2 2p2 1s2
• •
Ne
Li
H
X
Be
O
Be
N
C
Name_____________________________ Period_________ Wavelength Worksheet
WS5.1
Please show your work, not just the answer ď Š. If you look down from Diamondhead in Hawaii, you will see waves rolling in at a steady rate. Some days they are nicely spread apart, meaning they have a long wavelength. Other days they come in more frequently; this is more dangerous for the surfers. The surfers prefer the long wavelength days. They know that as the wavelengths get shorter, their frequency gets higher, and there is more energy- more danger – to the high frequency waves. This is summarized in the diagram:
Light travels in the same way. It travels at a steady rate: about 300,000,000 meters per second, or 3 x 108 m/s. And as the wavelength decreases, the frequency must increase: Wavelength Formula Our eyes are really important to us, but they are kind of lame when you consider the tiny portion of light S = wf from the electromagnetic spectrum that theyincan detect: S = speed of light = 3 x 108 m/s w = wavelength meters (m) f = frequency in waves per second (Hz, or s-1) Wavelength Chart
We can use the wavelength formula and the chart on the previous page to understand things like radio stations, visible light, and sunburns (due to ultraviolet light). Our ultimate goal is to make the connection between light and the electron.
Example. What is the frequency of green light, which has a wavelength of 4.90 x 10- 7 m? Solution: s wf; f
s 3 x 10 8 m/s 6.12 x 10 14 s -1 w 4.90 x 10 -7 m
In addition to a scientific calculator, you will need to refer to the wavelength chart on the previous page to answer these questions. 1. An X-ray has a wavelength of 1.15 x 10-10 m. What is its frequency?
2. What is the speed and wavelength of an electromagnetic wave that has a frequency of 7.8 x 106 Hz? 3. A popular radio station broadcasts with a frequency of 94.7 megahertz (MHz). What is the wavelength of the broadcast? (1 MHz = 1,000,000 Hz)
4. Cable television operates at a wavelength of about 1300 nanometers. What is the frequency of that wave, and what region of the electromagnetic spectrum is it in? Is it dangerous? (Any wave more frequent than visible light is considered dangerous).
5. Which is more dangerous, a radio wave or ultraviolet light?
6. The moon is 234,000 miles from earth. Light travels at 3 x 108 meters per second, and there are 1.62 kilometers in a mile. When you shine a flashlight on the moon, how long does it take for the light to hit the moon?
7. The smallest particle of light is the photon. Max Planck discovered that the energy of light can be calculated, where it is simply equal to a constant number multiplied by the frequency of the light: What is the energy of a photon of green light? Light Energy Formula: (See question number 1) E = hf Where E is the energy of the light in joules h = Planck’s Constant = 6.626 x 10-34 joules .seconds f = the frequency of light in Hz (which is 1/seconds) 8. What is the energy of a photon of light with a wavelength of 2 meters?
9. Since s = wf, and E = hf, can we calculate energy using wavelength, by combining the two formulas? Please show the combined formula. (Hint: note that f appears in both formulas).
Name____________________________ Period_______
WS5.2
The Bohr Model of the Atom Prior to the work of Niels Bohr, it was known that electrons existed outside of the nucleus, but beyond that very little was known. 1. What was the observation that Bohr based his research on?
2. The Balmer formula is : Solve this formula for n = 4.
w
1 1 1 0.01097 2 2 n 2
3. The heart of Bohr’s discovery was that he was able to come up with real meaning to this formula. Draw a hydrogen atom with several energy levels (“shells”) around it and show electronic emission from the fourth shell to the second shell.
4. Draw diagrams indicating atomic emission and absorbance.
5. All of the visible atomic emissions for hydrogen enter the second energy level. What wavelength of light is emitted when an electron moves from the second energy level to the first energy level? What type of light is this?
Name:_______________________________________
Period:______
WS5.3
Electron Configuration (L1 only) Directions: Draw the electron configurations with orbital notation for each of the following atoms. Example: Here is the electron configuration of Sulfur with orbital notation. 16S:
1. Scandium:
1s2 2s2 2p2 3s2 3p4
2. Gallium:
3. Silver:
4. Krypton:
5. Iron:
6. Bromine:
7. Californium
8. Write the electron configuration using shorthand notation of the following elements: a. sodium
b. An oxygen anion, O-
c. Radon 9. Two substances that have the same number of electrons are isoelectronic. For example, both the fluorine anion F- and neon have ten electrons, they are isoelectronic. a. The bromine anion is isoelectronic with what uncharged element? b. Argon is isoelectronic with which monocation?
Name___________________________________ Period __________________
WS 5.4
Electron Configuration NOT! Worksheet (L1 only) In this unit we have seen how the electrons are organized around the nucleus. It is a very detailed view of the electrons location, and various rules to help keep it all straight have been devised, and are shown below. In each problem below, the electron configuration is incorrect. Fix it, and explain what law or principle (not Principal!) was violated. EXAMPLE: Law Violated: Aufbau Principle Fixed: 1. 1Hydrogen:
2s1
1s
Principles and rules of electron configuration Principle or rule Heisenberg
Bad
Good
1s22p1
1s22s1
(e-position uncertain)
Aufbau (build up) Hund’s Rule (spread out) Pauli (opp. spins)
1
1s22s22p2 1s2
Unit 5 electrons Dr. B.’s ChemAdventure
Law Violated: __________ Fixed:
2. 17Chlorine
3. 39Yttrium (next page)
1s2
2s2
2p6
3s2
3p5
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
1s22s22p2 1s2
Law Violated: __________ Fixed:
Laws Violated: __________ Fixed:
4. 8Oxygen 5.
1s2
2s2
2p4
106Seaborgium
1s2
2s2
2p6
Law Violated: __________ Fixed:
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
4f14
5d10
6p6
7s2
5f14
6d4
Name:_______________________________________
Period:______
WS 5.5
Electron configuration and orbital notation self test Chemical behavior is determined by electron position. It’s a simple statement, but it says a lot. Another way of saying it is “Chemistry is all about where the electrons are”. That’s why we’ve been spending the last week focusing on electrons. However, somehow it always seems to bog down in some weird world of 1s2 2s2 2p6, and the Pauli Principle, and we forget our goal: if we know where the electrons are we know how the substance will behave. Why Neon is stable, and sodium is very unstable, and in fact why all the elements and the substances they form behave the way they do. Let’s pick an element. We know that oxygen contains ___ protons. And since it is not charged, it contains _____ electrons. We know that ____ of the electrons occupy the first shell, and the other six are in the second shell. We know that the first shell consists of a _____ orbital that holds _____ electrons, and so we say that the electron configuration of that first shell is 1s2. For the second shell we have six electrons, and we have learned that the first two will occupy a ____ orbital, and the next four go into ____ orbitals. Thus the electron configuration of oxygen is____________________. We can go into more detail, and show the exact orbitals that the electrons are in, which even show the direction the electrons are spinning in. An atomic orbital is simply a ______ of electrons, and the Pauli Principle tells us that electrons prefer to pair up with _________ spins. The first shell of oxygen contains one orbital, which we draw with a box like this:_______, showing that the electrons are paired up with opposite spins. The second shell begins with one more orbital for the two electrons of the 2s subshell, for a total of four electrons so far. We have ______ more electrons in oxygen, and they will occupy the three p orbitals. We remember to apply _________’s rule and spread these electrons out as far as possible in those three boxes. Thus we can draw the electron configuration of oxygen with its orbital notation right above it:
Note that this tells us that oxygen has four electrons in its outer (second) shell, and the two of them are unpaired….we also know from HONC that oxygen likes to form two bonds…a coincidence?? Let’s work out the electron configuration of nitrogen and see if we get three unpaired electrons: Nitrogen has _____ electrons, so the electron configuration with orbital notation is (be sure to spread out your p electrons): Does this orbital notation show 3 unpaired electrons?? If this makes sense, continue to the “how to ace it” guide.. If not, see me so we can do more examples.
How to ace the Electrons Exam
Howtoaceitunit5
In this Unit our goal was to determine where the electrons are in atoms. To find out, we performed two experiments that revealed the sharp lines that excited pure elements produced. We then analyzed this data from a historical perspective, beginning with the work of Niels Bohr. For this we needed to review the properties of light, including frequency, wavelength, energy, and, common types. This involved the use of the speed of light equation (s = wf) and an understanding of the electromagnetic spectrum. We then showed how the key mathematical solutions of Balmer and Rydberg allowed Bohr to put it all together to postulate energy levels, where atomic emission explains light, and produces the spectral lines observed for all elements. This was followed by a detailed look at the electron around the nucleus. We found that not only do electrons reside in shells, there are also subshells or orbitals within each shell. We observed how they spread out within an orbital (Hund’s Rule), and even how they spin when near each other (the Pauli Principle). We learned the configurations of electrons for all elements following the Aufbau Order, and how to write it all down by electron position, configuration, or orbital notation. This can rapidly tell us how many electrons are in each shell and subshell, the spin of each electron, and the number of unpaired electrons. The limits of observation of the electron are a result of the Heisenberg Uncertainty Princliple, which states that it is impossible to measure the position and velocity of an electron simultaneously, due to the extreme sensitivity of the electron. Finally, we showed how valence is easy to determine using the periodic table, and that valence may be drawn using electron dot formulas, also known as Lewis Dot Formulas. During this study we found that the periodic table is well designed to show the number of valence electrons for any element. In our next unit we will apply this to our understanding of the periodic table. To dominate this test, review all of the material in his packet: The lessons, the labs, and the worksheets. Here is some of the key information you should know: To ace this exam you should know:
1. Draw the symbols for Democritus, Aristotle, Ghazali, Lavoisier, Dalton, Thomson, Rutherford, and Bohr 2. What is the significance of each symbol? Try to assign one or two key words for each symbol. 3. What are the dangerous wavelengths of light? 4. How does light relate to electrons? 5. What is wavelength? Units? 6. What is frequency? Units? 7. Rearrange the speed of light equation to show what frequency is equal to. 8. The electromagnetic spectrum: what is it? 9. Frequency: how does it relate to energy and safety? 10. Wavelength- how does it relate to frequency? 11. Energy: which rays have the highest energy? 12. Safety: why are radio waves generally considered safe? 13. Types of radiation Really long waves include ___________ and _______________; really short waves include __________ and ____________. The ___________________ (long/short) waves are dangerous. 14. Convert 452 nanometers to meters (107 nm = 1m) 15. Use s = wf to find the frequency of 452 nm light. 16. (Level one only) The Balmer formula. Find it in your notes: 17. Significance 18. Solve for the n= 3 to n = 2 transition: 19. Atomic Emission Spectra: How did we observe it? 20. Emission vs. absorbance- what is the difference? 21. The Bohr model of the atom- draw a model 21.5 What is the difference between electron configuration, and orbital notation?
22. Electron names to zirconium. For example, manganese has the symbol ____ 23. L1 only: Electron configurations- all elements…do iodine using noble gas notation. 24. L1 only: Orbital notation: all elements. Do silicon. Include the number of valence electrons, and the number of unpaired electrons. 25. The Heisenberg Uncertainty Principle. State what it is and why briefly. 26. L1 only: Orbitals: s, p, d, and f…how many electrons for each? How many orbitals for each? 27. L1 only: Aufbau principle. Give an example where it is broken, and fix it.
28. L1 only: Pauli exclusion principle. Break it and fix it.
29. L1 only: Hund’s Rule. Break it and fix it.
30. Lewis Dot Structures. Draw oxygen, for example
31. Valence Electrons. Do each column in the periodic table..
32. Why is it important to use scientific references, rather than websites, when writing a scientific paper?
33. Where are the electrons in an atom?
The Periodic Table Unit 6 What is the periodic table good for? Introduction
The universe is composed of approximately 120 elements. These are pure substances with a fixed number of protons: hydrogen has 1, helium 2, carbon 6 etc.
They could be listed in a few rows:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
But that wouldn’t really tell us much. Or maybe they could be organized another way, since for example 5 x 4 x 3 x2 x 1 = 120… but would there be a reason for organizing it that way? If the universe only has about 120 elements, it seems reasonable to expect some sort of organization to them. That is what the periodic table is about: trying to figure out how the most basic matter in the universe is organized. But there’s a problem. The periodic table just doesn’t look right. Here it is below: An important concept in science is known as Occam’s Razor, which suggests that the simplest
answer tends to be the right one.
In the table on the left most rows and columns are of different length, and it is in two pieces. This is not a simple table. Could it be that we humans just haven’t figured it out yet? I’m hoping you can do better. Somebody should.
Our Essential Question:
O O O
O
OH H
NH O O OH
OH
O O
O O
1. taxol (paclitaxel)
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Our Essential Question:
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r r r r r r r r r
I
W 1. 2. 3. 4. 5. 6. 7. ______ ______ ______ ______ ______ ______ ______ 1. ________ 2. ________ 3. ________ 4. ________ 5. ________ 6. ________ 7. ________
W
stock value 
new price x investment original price
O
I H OH
O O
O
OH
H O
H
NH O
O
O
OH
OH
O
O HO
H O
O O
O OH O
H
O O
O
O
O
H
O
O OO O
1. taxol (paclitaxel)
N
azadirachtin
O
N
O
O
N
N
OH
O N Co N N
N 3+
R
N
HO
N
O
O
O
P
O O
O
O O
3. Vitamin B12
N
O
OH O
H O O H O
H
H O
H
OH OH 4. ginsenoside rb2
N O
OH H
OH HO
O N
HO
OH OH
OH OH
O O
OH
I
HO HO Na O S O O O
OH
HO HO HO
H O
H
OH
HO
H
OH
O H
H O H
O H
H O
O H HO H
H O H
O H O
O
H
H
HO
H O H H
OH OH O O O S O OH Na H O H
H O H H O H H
O H HO H H
HO HO
O H
O
HO
H
O H
H
O H
O
H OH
O
HO
O
H
H OH O H
O
OH H HO
HO
H OH
H OH
HO OH H HO O H HO
H O
O H
O H O H
OH
M
Lithium
Sodium
Beryllium
Magnesium
Potassium
Calcium
Rubidium
Strontium
Boron
Aluminum
fluoride
bromide
permanganate
bicarbonate
Chloride
hypochlorite
iodide
chlorite
Cesium
Barium
Francium
Radium
nitrite
perchlorate
Ammonium
Zinc
nitrate
bromate
silver
oxide
sulfide
chromate
dichromate
chlorate
bisulfate
hydroxide
cyanide
iodate
carbonate
sulfite
sulfate
nitride
phosphide
acetate
phosphate
C
O
Br N
H O
Si F Li
O
Na
W
+
N
0
+1 +2
+3
polyvalent
-3
-2 -1
F
O
G
D H H N C H H C H H H
and
H H C H N H C H H H
U
O O
+
O
-
I
W
C
r r r r
Our Essential Question:
Our Essential Question:
W
r r r r r r r r r
Watch each reaction, write a balanced chemical equatio, and describe the reaction type:
Going deeper: not all reactions fit into these categories (esterification, for example.
Watch the video and ask yourself if both reactants are fully consumed (did they waste anything?) “expert” answer
My answer:
How do we avoid wasting reactants if they are too small to count? My answer:
“expert” answer Some relative masses
Relative mass in grams = Molar mass
Watch the reaction, then provide a one mole scale recipe
Watch the reactions, then answer the questions equation reactants products moles
grams
Reaction type
Signs of a reaction Acids or bases? Solvent?
1. Ice melts. What are the COOL signs of a chemical reaction you observe? Is it a chemical reaction? 2. Wood burns. What are the COOL signs of a chemical reaction you observe? Is it a chemical reaction? 3. Iron rusts. What are the COOL signs of a chemical reaction? Is it a chemical reaction?