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 Blackboard - Discussion Pages

Charles E. Ophardt, Professor of Chemistry, Elmhurst College, Elmhurst, IL 60126, charleso at elmhurst.edu, Copyright 2004

TOPIC 2: INTRODUCTION TO CHEMISTRY

ON-LINE Lecture Discussion Requirement:

Do one question from the QUES 1 - 10. Student ID number assignments are as follows:

 Questions  Ques. 1  Ques. 2  Ques. 3  Ques. 4  Ques. 5
 Student ID  9, 17 27  10, 18, 28  1, 19, 29  2, 20, 30  3, 11, 21
 Questions  Ques. 6  Ques. 7  Ques. 8  Ques. 9  Ques. 10
 Student ID  4, 12, 22  5, 13, 23  6, 14, 24  7, 15, 25  8, 16, 26


Everyone should do Question 11 - write a short element report.

A third question may be to respond or comment to someone else, or use General Questions to ask a general question the Prof or others might answer.

Check answers already completed in
Blackboard - Discussion Pages

Write out answers to questions in a WORD PROCESSOR
and then copy and paste into
Blackboard

Requirements for the Lecture On-Line Discussion
Method to list references and citations.

TEXT READINGS: Chapter 1, Chap 3, Chap 4

In both of these topics 2 and 3, do not be overly concerned about the large amounts of text material that have been assigned, read mostly for an overview in most cases. Try to be more specific to answer the questions both here and eventually on an exam. Many times in the course I will refer you back to these pages as necessary. The same thinking should be applied to looking at some of the internet sites, use them to get some additional understanding, but do not feel that you have to absolutely understand every last item. And, it is not necessary that you look at every site that I have found, I would hope that you would look at some of the notes and graphics that I have made and would usually talk about in lecture. These are denoted as "ProfONotes". I will not test your "memory" of these topics, but will be looking for demonstration of an understanding of the basics with full resources available.

 

 1. Physical States of Matter - solid, liquid, gas

Text: p.1-7

States of Matter

 Use Hydrologic Cycle with water as examples Text p. 282-3
ProfONotes: Water Cycle

NOTES: The hydrologic cycle is a way of thinking about how water circulates from lakes, oceans (liquid state) to the atmosphere (gas state) and back to the surface of the earth as precipitation (rain-liquid, snow, ice-solid ).

 QUES 1: What other terms can you think of that relate to changes of "state" or form for water such as transpiration (change of water to vapor or gas state from the leaves of plants), evaporation, condensation, etc.? Give examples and definitions.

Can you think of any other examples using other substances (besides water) of the three states of matter.

 Text p. 282-3

ProfONotes: Water Cycle

2. Classification - Forms of Matter
 A. Mixtures - Homogeneous vs. Heterogeneous; Solids vs. Solutions

Text p. 7-9

ProfONotes: Mixtures
ProfONotes: Matter
ProfONotes: Compounds

 B. Pure Substances - Elements and Compounds (Graphite, Diamond, sodium chloride crystals)   Text p. 9-10
 C. Atoms and Molecules Text p. 10-13
 D. Acids, Bases, and Salts; Organic Molecules (very brief look ahead)  Text p. 180-4

 

 QUES 2: Define the above terms mixtures; pure substances; atoms and molecules; acids,bases, and salts; and give examples. See 2A-d on the outline. Be sure to explain and contrast homogeneous vs. heterogeneous; elements vs. compounds; atoms vs. molecules.

Various students could answer this partially and others could complete it, expand or give some other examples. Each student should do two things.

One person can use the text p. 16 to explain what the pictures mean in Fig. 1-6.

 Text p. 7-13

3. Physical and Chemical Properties and Changes in Matter
 A. Physical Properties and Changes  Text p. 3-6
NOTES: The main idea is that in physical changes, the atom, compound, or individual molecules remain intact through all of the changes. The same atom or molecule is present at the beginning and the end of the physical change. The water molecule H2O is always present in ice, water, and water vapor.
 B. Chemical Changes and Properties  Text p. 3-6
In a chemical change, the basic molecular structure is altered - bonds are broken in some molecules and the atoms are rearranged to form new bonds and new and different compounds and molecules are present at the end of the reaction. Electrons are involved in the formation and breaking of the bonds between atoms. The nucleus is not involved in a chemical reaction. In the electrolysis of water, electricity is used to break the bonds in the water molecule (H2O) to make molecules of oxygen (O2) and hydrogen (H2). p. 38-41
 C. Nuclear Changes - very brief; such as the protons and neutrons change in the nucleus (further work in Issue 2.  Text p.117-121
In a nuclear change, the nucleus is changed by the addition or subtraction of protons and neutrons. Some particles are emitted from the nucleus in the form of radioactivity. In these nuclear changes, new elements are formed.

Notes: The difference between the physical and chemical properties of copper. Pure copper has a bright orange type color as a physical property. However a chemical change can occur with copper in the air to produce a green color which is really a combination of copper oxide and copper carbonate. A chemical change has produced new compounds which have a different physical property, namely the green color on the surface of the copper metal. Silver has the same property of tarnishing (turns black due to the presence of silver sulfide). Gold does not have this chemical property and does not tarnish or change colors.

 QUES 3: First, pick an example of any everyday object, then describe one physical and chemical property. Second, give some examples of chemical and physical changes.

If you run out of those kinds of ideas, then use examples from some things that you do in the kitchen.

 Text p. 3-6

Notes: For Example: When you bake a cake, is this a physical or chemical change? You should observe that the cake rises due to blowing bubbles of carbon dioxide. Since new substances are formed, it is a chemical change.(You could have answered this much by yourselves) Further explanation: It is a chemical change because you have added baking soda or baking powder as an ingredient. You have also added some form of acid, probably hidden and you do not know about this, which in turn reacts to produce bubbles of carbon dioxide.

4. Law of Conservation of Mass
A. What is the Law of Conservation of Mass? Text p. 57
Law of Conservation of Matter and Energy

 B. Consequences of Throw Away Society - Pollution

1. Quality of Matter: High Quality (high concentration, relatively pure)

vs.

2. Low Quality Matter: (low concentration, impure, polluted.)

 Text p. 57
NOTES: Organized and concentrated matter is high quality matter that can be converted into useful products. Low quality matter has been changed, disorganized, or dispersed after it has been used and thrown away. In a "throw away" society, everything that is thrown away is still with us in one form or another; there is no "away". Pollution is caused by misplaced matter or waste products that were changed into other forms of matter that went down the drain or up the smokestack or to the landfill.
 C. Sustainable Recycling Society  Text p. 563-4

QUES.4: State the Law of Conservation of Mass and apply it to the burning of a candle or gasoline in your car.

How does it relate to a "throw-away" philosophy in society?

Give an example of "high and low" quality matter.

Text p. 57

Law of Conservation of Matter and Energy

5. Atomic Structure (read Chap. 3 - all of it)

A. Parts of the atom - electrons, electricity, cathode ray tubes, Thomson's mass to charge ratio, Millikan's Oil
Drop experiment.

 Text p. 60-65

Science Trek Contents - For a series of animations on electrons, scroll down to the quantum atom and try some of the animations - it will help you understand how electrons behave.

Discovery of atom particles -

QUES. 5: Review some of the experiments, especially the cathode ray tube involving the discovery and properties of an electron.
Also include ideas relating to the attraction and repulsion of different charges.

 Text p. 60-61

Cathode Ray Tube or Crooke's Tube - good animation and explanation.


B. Parts of the atom - protons, Goldstein's hollow cathode Text p. 61-62

QUES. 6: Review the Goldstein Experiment with perforated cathodes. Also include ideas relating to the attraction and repulsion of different charges.  Text p. 61-63

C. Parts of the atom - neutrons  Text p. 64-65
D. Structure of the atom - nucleus, Rutherford Gold Foil Experiment, Atomic Number, Atomic Mass, Isotopes  Text p. 62-64
Electrons, Protons, and Neutrons: For any atom use the Periodic Table and be able to give the number of each that are present. Example: Sodium, Na: Atomic Number = 11 = 11 protons = 11 electrons; Atomic Mass = 22.99 (round to nearest) = 23 = total protons + neutrons; therefore 23 - 11 protons = 12 neutrons.
Rutherford Gold Foil Experiment: (A GIF animation (180K) from Sam Houston State U.) Alpha particles ("atomic bullets") were directed at a very thin piece of gold foil. The particles were expected to pass directly through the gold foil, however some of them were deflected at various angles. This was interpreted as evidence for a very dense nucleus in the atoms containing the protons and neutrons.

QUES. 7: Explain the Rutherford Gold Foil experiment. Why do most particles pass right through; why are some deflected? What is the final conclusion of these experiments relating to the structure of the atom?

 Text p. 62-64

Rutherford Gold Foil - animation - different from the above animation.

E. Structure of the atom - arrangement of the electrons and the Bohr atom.

 Text p. 83-87

Spectral Lines of the Elements -Explanation
Bohr's Explanation of the spectra and electron arrangements

Periodic Table click element to see emission spectra

Bohr Model Atom: From the evidence of "line spectra", only certain bands of colors are observed various types of elements, Bohr hypothesized that the electrons are only in certain orbits around the nucleus of an atom (similar to the solar system).
 Quantum Wave Model Atom: The Bohr model of the atom using electrons as particles in a solar system type arrangement was later replaced with the quantum wave model. Electrons behave as waves, not as particles, and as a results the electrons are described mathematically to have only certain probabilities in certain regions of space around the atom. The energy levels are further divided into sub energy levels denoted as s, p, d, and f.

 QUES. 8: Explain how fireworks and line spectra were used by Bohr to give the first explanation of the arrangements of electrons in an atom. Give an example of a Bohr Diagram.

 Text p. 82-87

Periodic Table - gives a graphic picture of the Bohr Diagram of each element. First select an element, then at the top of the frame, click on Atomic Structure to see the Bohr Diagram.

 QUES. 9: Explain the concepts of the Quantum Wave model of the atom. What are meant by electron configurations? Give an example.

 Text p. 87-94

Periodic Table - gives a graphic picture of the Bohr Diagram of each element. First select an element, then at the top of the frame, click on Atomic Structure to see the Bohr Diagram.

F. Specific Elements - use Periodic Table to give electrons, protons, neutrons
Bohr diagrams, Lewis symbols, General organization of Periodic Table

Text p.70-73
 Periodic Table - gives a graphic picture of the Bohr Diagram of each element. Pick an element, then you can look at the Bohr diagram by clicking on electronic data or the picture of the Bohr Diagram.

A little music to brighten your day. Tom Lehrer's Element song.

 G. Isotopes - of elements have the same number of protons, but different numbers of neutrons. Isotopes have different atomic masses as a result.  Text p.67-69


QUES. 10: After reading through this material and/or reading responses for questions 7, 8 and 9, give a brief explanation of the structure of an atom of carbon, nitrogen, oxygen, sulfur, or chlorine as you might explain it to a friend. Use some details about the number of electrons, protons, and neutrons. Also talk about the particles in the nucleus from the Rutherford experiments and the specific location of the electrons from the Bohr Atom theory. Each student pick one atom.

Chap. 3 and 4

 

Periodic Table - gives a graphic picture of the Bohr Diagram of each element. First select an element, then at the top of the frame, click on Atomic Structure to see the Bohr Diagram.

 QUES. 11: EVERY STUDENT DOES THIS QUESTION.

Choose ONE element except H, O, C.
First look at the Discussion board to find an element different from those already posted.
Use the internet sites, the text book, or a Science encyclopedia to find as much as possible of the following information. Natural source of the element including its natural state (solid, liquid, or gas), compound or mixture it is found in, products and compounds made with the element, uses of the element, and any other interesting details.

Other items to include are: Name, symbol, number of protons, neutrons, electrons, Bohr Diagram, a physical and chemical property,

Write a short report to summarize your findings. Put this into your own words and do not just copy and paste some of the info.

Three Periodic Tables among many on the web. Use at least one of them.

WebElements- Scholar Edition - Data, description, uses, historical, be sure to click some of the items in the left menu bar.

Periodic Table at Los Alamos Lab - contains information about each element.

Periodic Table - gives a graphic picture of the Bohr Diagram of each element. First select an element, then at the top of the frame, click on Atomic Structure to see the Bohr Diagram.

It is also OK to use Wikipedia.org. They probably have more than what is in the periodic tables above. Just type in the element name in the search box. Pick out somethings that interest you and report on them. Still complete the items on the left.