Chemistry

Chat times for 2012/2013
Mon 9am ET/6am PT
Thu 8pm ET/5pm PT
Dr. Christe Ann McMenomy

Lesson Schedule

Student Survival Guide

Or: How to survive a science course, with special attention to the problems of studying chemistry

Why Study Science?

At the heart of all science is something called the scientific method. The simple version of the scientific method is based on the idea that the objective reality of the universe can be determined by carefully observing phenomena, recording appropriate measurements, then studying the data from these observations for patterns that can be used to describe the general behavior of classes of natural objects. When we can control the circumstances of the observations, we are performing experiments, but often we cannot control all the factors before we make observations. There are scientists who believe that the only valid scientific data is that which comes from controlled experiments; in their view, most of astronomy, meteorology, geology, and many parts of biology are not rigorously scientific. Since this is a chemistry course, in most cases we will be working inside the experimental tradition.

Man's search for patterns led him to keep track of many chemical phenomena from very early in recorded history. Combinations of leaves from different plants, or from powdered seashell, produced medicines and dyes. Some kinds of dirt could be heated, yielding metals that could be forged and shaped into tools and weapons. Over time, scientists recorded these similarities in behavior and structure.

When scientists find similarities between objects, or patterns of behavior that repeat with little variation, they want to study them to see if there is some common cause behind the similarities. When the scientist finds a reasonable explanation, he or she proposes a hypothesis, a testable statement about the phenomena. Hypotheses that stand up over many repeated observations are combined to make theories; distillations of theories that have no known exceptions may be called natural laws. In chemistry, we are particularly concerned with theories of matter, chemical reactions in which combinations of matter change into new combinations, electricity generated from chemical reactions, and energy transfer.

The Science Course Online

Science classes are frightening for many students. They anticipate difficulties with the concepts, with the details, and especially with the math. But science is just one way of thinking about the natural world around us, and anyone can learn to think like a scientist. Don't waste energy worrying about your ability to learn the material; use your energy to learn it! Once you get the hang of it, you'll be able to discover, understand, and appreciate the complexity of God's creation better. You will also be better prepared to take your place as a steward of that creation.

Review the prerequisites for the course. These are the concepts and math skills that you should have mastered in order to succeed in learning the material. The math prerequisites for this course are described in the FAQs page. If you have any questions about your readiness for the course, be sure to ask for help during our first session. I will arrange to work with you so that you can gain the required skills quickly.

Every science course has as its main components lectures, reading assignments, labs, and lots of homework to prepare you for taking quizzes and exams. In addition to these, our online course has this website, the conference center, and e-mail to provide the functions that would normally exist in talking to your teacher face-to-face, or looking at a bulletin board or whiteboard. Keeping track of all the components can be a daunting task, especially at first, so plan to spend some time becoming familiar with the course website, your text and the CD, and the bulleting board. Once you have mastered the mechanics of using these tools, you can concentrate on learning the material that they contain.

Why are there so many parts to the course? Well, part of the reason is that you learn in many ways. You memorize facts, you comprehend relationships, and eventually, you understand concepts. You learn by reading, by seeing pictures and graphs, by watching demonstrations of processes, by participating in discussions, and by applying what you are learning to specific situations in the homework and labs. You "cement" what you've learned by teaching others. The organization and materials of the course require that you take all these approaches.

Managing Your Time

Make the commitment, now, to spend adequate time on coursework. This chemistry course may challenge you mathematically as well as conceptually, so you must realize right from the start that you cannot do all the work for a given unit on one day ... and you shouldn't do it just before chat session! The table below is a rough guide and a suggested pace for this course. The amount of time you spend on each part of the assigned work will vary greatly from student to student, and your schedule will of course depend on your other commitments. Work out a reasonable work load and stick to it!

Try to do your reading as early as possible. This allows you to think about the questions and material, review it in your mind, and absorb it more critically.

Note: You may find it beneficial to work through the IC sections before tackling the textbook; if so, reverse the order of 3 and 4 below!

Checklist for normal schedule

Completed? Task Approximate Time Scheduled for...
1 _____ Check Website for instructions 15 minutes Monday/Wednesday after chat
2 _____ Read Web Lecture 1/2-1 hour Monday/Thursday
3 _____ Read Text Assignment 1-2 hours Monday/Thursday
4 _____ Work through the CD-ROM Tutorials 1-2 hours Tuesday/Friday
5 _____ Complete Homework 1-2 hours Wednesday/Friday(Sat)
6 _____ Post assignment to conference center 15 minutes Before class
7 _____ Make observations for lab 1-2 hours
8 _____ Perform calculations/reduce data 1 hour
9 _____ Write lab report 1 hour
10 _____ Take online quiz 15 minutes (only at the end of the chapter)

Web Lectures

Rather than take our precious chat time by lecturing to you, all unit lectures are posted to the site. You need to read these as well as the text. Most of the Web Lectures have a

  • main lecture with further detail on some area of the text presentation
  • practice with concepts (checkpoints for your understanding)
  • list of discussion questions to prepare for chat
  • optional website readings for your copious free time.
  • [study guide notes are on the homework assignment page]

The "checkpoint" exercises ask you to figure something out, then offer you the opportunity to check your answer. Try to figure things out before hitting the "answer" button! If you were correct, and your reasoning was correct, congratulations! You are ready to continue with the next concept. If you missed the answer, but understand the correction, make a note to review the concept later. If you don't understand the explanation, ask the teacher during class, or send e-mail requesting further help.

As you read the web lecture, make notes on anything that puzzles you, and be sure to raise your questions in class.

Getting to Know the Textbook

Read through the Preface for Kotz and Treichel's Chemistry and Chemical Reactivity, 5/e.This describes the features and layout of the text and CD-ROM.

Each chapter has text, graphic materials, examples, and exercises. If you have not taken a physical science course before, you may not have run into the use of extensive examples in the text. Sometimes you may figure they aren't worth the time it takes to read them, but don't be misled by this sensation! You should work through every example in the text carefully. Make sure that you understand

Test your understanding of each section by attempting the exercise at the end of the section and checking your answer against the answer in the back of the book (the "AITBOTB").

Getting to know the CD-ROM Contents

Follow the instructions for installation for your platform. Check the README.txt file for platform requirements. You need to have QuickTime and Acrobat Reader installed; instructions for installing the correct versions are included in the Tools folders on the disk.

Then spend some time becoming familiar with the different programs on your CD-ROMS. The two discs each contain all tools (these are reached from inside the Chem Interactive program); Disk 1 contains material on chapters 1-10 and disk 2 on chapters 11-20.

Start up Disk 1, click on the opening page, and then on the Chapter 1 (Introduction) link. You'll see that the Navigation bar at the left has a set of numbers corresponding to screens, and links to Contents, Index, existing the program, and the tools: Periodic Table, Molar Mass Calculator, Molarity Calculator, Molecular Models, and Plotting Tool. We will use these in the course of going through specific exercises in different chapters.

As you look at screens, note the red arrows that start animations, tutorials and videos. In particular, look at the Introduction screesn 1-11, which discuss the general nature of studying chemistry, and the particular features of the CD-ROM, its organization, animations, exercises, and tutorials.

Doing Homework

Homework is not merely useful, it is essential for mastering the concepts of a science course. You will know whether you understand a concept if you can use it to solve a "real-world" problem, and when you can teach it to someone else. We use both techniques in this course. You will be assigned both word-essay questions and calculation problems for each unit. You should work all of these. You will also be asked to post the answer to at least one question and one calculation problem to the course conference center. This is your opportunity to explain to your fellow students what you know.

Your reading assignment will be on the Schedule page, along with my Web lecture and study notes for the assignment. You are expected to do all CD-ROM exercises and tutorials assoicated with the reading.

The assigned problems for each chat session and your individual posting assignment will be at the Bulletin Board thread for the chapter.

NB: mycroft, the original bot for my science classes, has long since been freed to do other things, like attend class, make obnoxious remarks, and aid stumped students. If you really get stuck figuring out the problem you've been asked to post, mycroft has been known to accept bribes in the form of virtual Oreo cookies to finish your problem for you.

Essay questions

Essay questions ask you to explain a concept in words. As you answer a science essay question, be prepare to cite calculation information as well as concepts, or give examples.

For example: What is the difference between a physical change and a chemical change?

A good answer will be grammatically and syntactically correct, using proper English, as well as contain the correct information. It will cover more than one point in supporting its argument.

A physical change does not effect the arrangment of atoms within a molecule, but only the relationship of the molecules of a substance to each other. When water changes from ice to liquid to steam, it only undergoes a physical change of state; the individual water molecules are always H20. A chemical change rearranges the atoms into new molecular structures. When an electric current is transmitted through water, H20 will break apart, forming O2 and H2 molecules, so hydrolysis is considered a chemical change.

Doing Math Questions

Most chemistry problems relating numbers of atoms to masses of a particular chemical. This is because it is easier to measure masses than to count molecules or atoms. But we need to know how many atoms or molecules we have, because chemical reactions occur by rearranging the contents of individual molecules. Other problems involve picturing the physical situation of a molecule and determining its size, or calculating the electrical attraction between molecules based on their distance.

Here is a "general problem solving" approach.

  1. Visualize the situation described.
  2. Identify and list all the knowns given in the problem and the unknown to be found.
  3. Set up a notation system for the knowns and unknowns, so that you can use the symbols in math relationships.
  4. Check for any hidden information — values that you know because of the situation, but which may not be explicitly given in the description.
  5. List everything you know and the unknowns.
  6. Look for a relationship that relates what you know to what you don't know. You need one equation per unknown value.
  7. Solve the formula for the unknown. Don't substitute values in prematurely: you'll only wind up doing more math.
  8. Once you have the final version of the formula in place, substitute the known values into place.
  9. Do the arithmetic.
  10. Check your answer for reasonableness, direction, and proper units.

Let's look at an example:

  1. Visualize the situation described. Be sure that you understand the concepts involved before you think about how they relate to a mathematical description. Here, visualize individual molecules in a drop.
  2. Identify and list all the "knowns" and the "unknowns". We know the density of water, and the volume of the drop. We do not know, without calculating it, the mass of the drop; we also need the mass of an individual molecule of water to determine how many "unit masses" are in the drop and hence how many molecules of water. But these can be determined.
  3. Set up a notation system for the knowns and unknowns, so that you can use the symbols in math relationships. V = volume of drop. Mass = mass of drop. rho = density of water = mass/volume = M/V. m = mass of individual water molecules. P = population of molecules in drop (what we want to find out).
  4. Check for any hidden information — values that you know because of the situation, but which may not be explicitly given in the description. The mass of a molecule of water must be determined; we know that water is H2O, so it has two hydrogens to each oxygen. Also, one milliliter (mL) = 1 cubic centimeter (cm3).
  5. List everything you know and the unknowns, in Standard units (meters, seconds, grams)

    V = 0.05mL
    rho = 1 g/cm3 = 1 g/mL [the commonly used symbol for density is the Greek letter rho]
    M = X gm
    m = x gm
    P = molecules (or moles)
  6. Look for a relationship that relates what you know to what you don't know. You need one equation per unknown value. In this case the relationship we need is the law cited above:
    P = molecules = M/m
    m = mass of water molecule = 2*mass hydrogen atom + 1 * mass oxygen atom = 18grams/mole of molecules
    1 mole = 6.022*1023 molecules
    rho = M/V
  7. Solve the formula for the unknown. Don't substitute values in prematurely: you'll only wind up doing more math.
    M = V * rho
  8. Once you have the final version of the formula in place, substitute the known values into place. Be sure to convert to common units! Do the arithmetic
    M = V * rho = 0.05mL * 1gm/cm3 = 0.05mL * 1gm/mL = 0.05gm. The drop masses at 0.05gm.
    P = M/m = 0.05gm/18gm/mole = 2.778 * 10-3 moles
    P(in molecules) = 2.778 * 10-3 moles * 6.022 * 1023 molecules/mole =
    1.6728 * 10-2 * 1023 = 1.67 * 1021molecules
  9. Check your answer for reasonableness, direction, and proper units.
    Since we have a fraction of a mole, we expect to have fewer molecules than there would be in a mole, and we do.

You are done!

Getting the Most from Chat

Chat sessions are 90 minutes. Plan accordingly, and take a break just before class starts. Do some stretching, go to the bathroom, eat or get your drinks before you enter the classroom. Be sure to try to connect to your ISP and check mail 10 minutes before class if possible, in case any late notices have been sent by the teacher. Give yourself the extra time. High traffic on your ISP or the school server can slow you down and force you to miss the first 5 to 10 minutes of class.

If you have not already done so, post your assigned questions and answers to the course conference center before the start of class.

Bring your text, notes, homework calculations, and paper and pencil to class. If you are comfortable using a desktop calculator and taking notes in a text utility like Notepad (available as different applications on both Windows and Macintosh), you can use those. Take notes during class. If you are logging, you do not need to document things the teacher or other students say, but it is useful to note your own questions and observations as they occur, so that you can study them later.

Take part in the discussion. Ask questions as they occur to you (or note them and ask them at the end of class).

Chat sessions in chemistry often involve discussion of mathematical calculations. Because of the limitations of chat entry, we cannot use super and subscript notations. The convention we use is underscore (_) for subscript and up-arrow (^) for superscript. The term x_1 ^2 means "take the value x-sub-1 and square it"; it may be more familiar to you as x12 but we can't write that in Chat. The chemical symbol of 2 hydrogens and 1 oxygen for a water molecule will look like H_2O instead of H2O.

Print the log out. As soon as possible after class, review the log and make notes on it about any points that bother you. Mark important points for review later. Save the log to review before the semester examinations.

Quizzes

All the chemistry examinations (quizzes, midterms, and finals) which I use to evaluate your understanding and progress in chemistry will be drawn from the homework questions in the text and study questions in the workbook. It is very important that you complete the homework problems, workbook exercises and study questions, and any essays I assign to prepare for the exams for this course.

There will be an online quiz for each chapter, which will be posted when we have finished discussing the material in the chapter. These quizzes include 10-15 multiple choice questions and are timed. When you take the quiz, you will receive an email copy of the quiz questions, your answers, and your score. In addition, the quiz site will maintain a record of your quiz work, and retain the score of your attempt. You should note the questions that you miss, and be sure to study the correct answers and the concepts behind them before the semester examination on the unit.

Most of the questions on the chemistry midterms and finals which I use to evaluate your understanding and progress in chemistry will be drawn from the online quizzes and homework. It is very important that you do the homework problems and take the online quizzes to prepare for the exams for this course. The online quizzes will help you prepare for similar questions on the SAT II Chemistry exam and the AP Chemistry examination.

Exams

Start your review two weeks prior to the scheduled examination.

Read through the chapter highlights at the end of the chapters that will be included in the examination. Make sure that you know the meaning of the boldface terms.

Go over your homework problems. Use the solutions at the conference center if you cannot redo the problem yourself.

Review the chat logs, and go over your notes.

Review your performance on quizzes, and make a list of the concepts with which you are still unfamiliar or which still puzzle you.

There will be two major exams (semester finals), one in January and one after the last lecture, which you will take during the first week or so in June. These will be mailed electronically to you, and you will take them with your parent or other responsible adult as proctor, and e-mail your answers back to me. Both exams contain a large multiple choice section with questions drawn from the CD-ROM and online quizzes, and math-type problems similar to our homework problems. Both sections will be closed-book. You may bring to these exams one 8.5 x 11 inch sheet of paper with whatever notes on it that you desire — so don't worry about memorizing formula. Learn concepts and applications!

Study Groups

Yes, of course you may study together — remember that explaining or teaching what you just learned to someone else is one of the important techniques of learning! You may also work together to solve the homework problems ... but be sure that you can solve them on your own afterwards, since you cannot work as a study group on quizzes or examinations. I encourage you to set up a regular meeting time outside our class discussion session for your study group.

Post the study time to the conference center. You may use the course classroom any time it is not already in use.

Doing Labs: The Scientific Experience

One of the basic methods of science is to secure documented observations of periodic or common events in order to make some general summary about the behavior of natural objects. We can do this in several ways.

Special concerns for Chemistry Labs

Chemistry, of all the sciences we teach at Scholars Online, poses the most dangers to the students. Glass equipment, sharp edges, bunsen burners, and chemicals that are able to burn or poison, are all hazards. While we try to use chemicals in dilute quantities, the possibility for harm cannot be reduced to zero. Before each experiment, review the safety guide and any safety information that comes with the chemicals and equipment that you may purchase.

Writing Lab Reports

Your lab report is the evidence of your observations of a particular phenomena. Your observations should be presented in such a way that the data is easy to understand and supports your conclusions, but also with enough detail on how you obtained them that any peer with similar equipment could repeat your experience and confirm your results (or challenge them, as the case may be).

Organization: A good science lab report has at least seven sections:

  1. The abstract: a short paragraph explaining the goal of the lab, the overall purpose or hypothesis, the type of data gathered, and the conclusions.
  2. Materials and equipment: a description of the consumable materials and the observing equipment, instruments used to collect data. For standard equipment, references to the make and model are generally sufficient, along with verification that the equipment was tested for proper calibration.. If the equipment was modified, or specially configured, describe the new settings. If the equipment was specially built, either summarize the intent and purpose of the equipment and methods of calibration, or refer to other documents which provide this information.
  3. Procedure: a list of steps taken to secure the data. This should be detailed enough to allow peers in the field to repeat the measurements you made under simillar circumstances. Any choices you made that might affect results should be stated, along with the reasons you made them.
  4. Raw Data: the numbers you copied from instruments, descriptions of what you saw with your own eys, notes to yourself about odd things that happened, and rough sketches made during the observation. They might also include photographs, data collected by computer, and so forth. In many cases, the amount of data collected this way exceeds the space available in a formal report, so you do not need to include all of it. You should select representative samples of this data, and retain your notebooks with the actual raw data for reference if anyone questions your results.
  5. Sample Calculations: at least one each of any calculations you did to determine reliability (statistical analyses) or to figure out derived data (e.g., density from volume and mass measurements). This allows a reviewer (such as your teacher) to determine whether you used the proper technique of data reduction in this situation.
  6. Processed Data: all the processed data on which you base your results in the most useful forms. Frequently this involves creating a table, and may additionally involve preparing graphs to show trends.
  7. Conclusions: your assessment of whether your originaly hypothesis or assumptions are supported by actual phenomena. If your results did not bear out your assumptions, but you still feel the assumption is correct, you should explain the source of the problem (errors in measurement, calculations, equipment), and outline a plan for redoing the observations. When your experiment bears out your hypothesis, your conclusion should place these results in the context of the large field, and could include suggestions for further research.

Resources

Obviously...

The Links option is a good source for current areas of chemical interest on the Web.

Current events....

Major upsets in theory show up from in news reports from time to time; a good source for these will be the "Science" section of news.google.com or the Yahoo news page.

Course wares...

Chemistry isn't the most popular science, but it does lend itself to modeling, something comuters are really good at. Your CD-ROM already uses many modelling techniques and data-reduction calculators.

In addition to molecular models, there are several virtual chemistry lab programs available. Watch this space for more information!

© 2012,2013 This course is offered through Scholars Online, a non-profit organization supporting classical Christian education through Internet-based courses. Permission to copy course content (lessons and labs) for personal study is granted to students currently or formerly enrolled in the course through Scholars Online. Reproduction for any other purpose, without the express written consent of the author, is prohibited.