Chemistry AP

Chat times for 2017-2018
Monday-Wednesday-Friday
10:30am-noon ET/7:30am-9:00am PT


Dr. Christe Ann McMenomy

Student Guide

Chemistry 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 the similarities to see if there is some common cause behind them. 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 course overview page and 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 Moodle, 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 Moodle. 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.

Checklist for normal schedule

Completed? Task Approximate Time Scheduled for...
1 _____ Check Website for instructions 15 minutes Monday/Wednesday/Friday after chat
2 _____ Read Web Lecture 1/2-1 hour Monday/Wednesday
3 _____ Read Text Assignment (and work through example problems!) 1-2 hours Monday/Wednesday
4 _____ Watch videos, perform simultions or Lessons 1-2 hours Tuesday/Thursday
5 _____ Complete Homework 1-2 hours Tuesday/Thursday(Sat)
6 _____ Post essays and assignment to Moodle 15 minutes Before due
7 _____ Complete AP example 1-2 hours Thursday (due Friday)
8 _____ Make observations for lab 1-2 hours Tues
9 _____ Perform calculations/reduce data 1 hour Thursday
10 _____ Write lab report 1 hour Tuesday or Thursday
11 _____ Take Moodle quiz 20-30 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. The Homework and Weblecture pages between them have

  • study guide notes to help you with the reading
  • a lecture that expands on the text or go into details about related topics
  • practice with concepts (checkpoints for your understanding)
  • lists of discussion questions to prepare for chat
  • a worked homework example
  • highly recommended website simulations or videos on specific topics
  • link to the associated lab

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. This describes the features and layout of the text, and some of the typographical conventions followed.

Each chapter has text, graphic materials, examples, and exercises. As you plan your workload, be sure that you give yourself enough time to

  • review some of the previous material, such as the key idea summary at the end of the last chapter
  • read through new material carefully
  • study the diagrams; some are "just for pretty", but most are integral to the presentation of material
  • work the example problems
  • check the vocabulary lists at the end of the chapter

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

  • how to interpret the question, so that you know what you are looking for
  • how to identify the equation or method to solve the problem
  • how to map the information in the question to variables in the equation
  • when to convert units, and why
  • how to perform the mathematical techniques involved and get a numerically correct answer
  • how to figure out the significant figures for the answer

Spend some time becoming familiar with your text. The periodic table inside the front cover is an important source of information for many homework problems; it will help you determine whether two elements are related and have similar characteristics, as well as providing you with important numerical information: number of protons and atomic weights, from which you can determine other information that may be needed to solve a problem. There are several appendices in the rear of the book as well that also contain critical numerical information you may need in problem-solving. Earlier chapters may include tables of information that problems in later chapters use; you may find it useful to photocopy these or at least to mark them with sticky notes or tabs to help you find them quickly when you need their information for homework problems.

TAKE NOTES! Outline the chapter, identify important terms, concents, and formulae. even if the text supplies you with an outline. After each section, write down the important points it makes, any items of particular interest, and any questions that you have.

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").

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a name="Homework">Doing Homework

Homework is not merely useful, it is essential for mastering the concepts of a chemistry course. Just as we test theories by applying them to experimental situations, you test your understanding by applying it to specific situations. 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 chat session. 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 Moodle. This is your opportunity to explain to your fellow students what you know. You will need to show your calculations and explain them in your posted answer. This is your opportunity to help to your fellow students understand a particular situation or problem-solving method.

Your reading assignment will be on both the Moodle and the Schedule page, along with links to my Web lecture and study notes for the assignment. You are expected to do any online exercises, videos, and tutorials assoicated with the reading that are mentioned in the homework page or weblecture.

The assigned problems for each chat session and your individual posting assignment will be at the Moodle forum for the day's chat.

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

Occasionally, I will assign as homework general questions that don't involve calculation. Essay questions ask you to explain a concept in words. As you answer a science essay question, be prepared 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.


a name="MathQuestions">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. Make sure that you understand what is happening in the real or idealized physical event.
  2. Identify and list all the known values given in the problem and the unknown to be found.
  3. Determine whether or not the units should be converted, and complete the conversion (e.g., one value is listed in grams, but your constant is in kilograms).
  4. Set up a notation system for the knowns and unknowns, so that you can use the symbols in math relationships.
  5. Check for any hidden information — values that you know because of the situation, but which may not be explicitly given in the description. For example, "standard condtions" usually means the temperature is 25°C and the pressure is 1 atmosphere.
  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. Make sure that your units will cancel to give you the correct units for the answer. For example, if you set up a formula to find concentration, and the units of the knowns cancel to liters per mole instead of moles per liter, you've done something wrong.
  8. Once you have the final version of the formula isolating the unknown and setting it equal to known values, substitute the known values into place.
  9. Do the arithmetic.
  10. Check your answer for reasonableness, and proper units.

Let's look at an example:

    A drop of water has a volume of 0.05mL. How many molecules of water are in a drop of water, if water has a density of 1.00 g/cm3?

  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 Moodle before the start of class.

Bring your textbook, notes, homework calculations, calculator, 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. You may also find a dictation program like Dragon helps reduce typing, either into chat or taking notes. Take notes during class. Since Scholars Online logs the chat sessions, 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 physics often involve discussion of mathematical calculations. One 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". You may be more used to seeing this written as x12, and we can actually do that in Dr. Bruce's chat, but it requires a bit of typing. If you prefer to use HTML tags, then here's a quick guide:

  • Subscripts are written with the HTML <sub> tag. Be sure to use the closing tag </sub> or you may wind up with material too small to read! The sequence v<sub>0</sub> typed into chat will look like v0.
  • Superscripts are written with the HTML <sup> tag. Be sure to use the closing tag </sup> after your exponent or indicator. The sequence 10<sup>3</sup> typed into chat will look like 103.
  • You can use unicode to indicate special characters. &alpha; will print as α, frequently used to designate angles. There is a good guide to unicode characters at TNT Luoma HTML Codes.
  • UPDATE for 2017 Dr. Bruce has implemented ASCIImath notation in the Scholars Online Chat. This allows you to type even complex mathematical formula relatively easily. To use the ASCIImath syntax options shown the ASCIImath.org site, type a RIGHT curly bracket symbol } as the first symbol on a line. Your entry will be translated before uploading to the server. A line like
    }F_g = (GMm)/r^2

    will appear as F g   =   GMm r 2

    Your teacher will provide more instructions during the first few chats.

After chat, log into the chat window again, hit the button for past chat logs, and print the log out. As soon as possible after class, review the log and make notes on it about any points that bother you, and be sure to ask about these in our next session. Mark important points for review later. Consult your notes or the Scholars Online copy of the log to review before the next session and before semester examinations


Quizzes

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

There will be an online quiz for each chapter, which will be available on the Moodle when we have finished discussing the material in the chapter. These quizzes include 10-30 multiple choice, short calculation, and other format questions and are timed. When you take the quiz, you will receive immediate feedback for your attempt. You will have a second chance to take the quiz for review during the grace period before midterm exams.


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 in the summary.
  • Go over the homework problems, both those you yourself posted and those posted by your fellow students, and try to rework the problems on your own. Use the solutions in the Moodle forums 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 several major exams (midterms), after major sections of the text are completed. These may be mailed electronically to you, or you may take them on the Moodle. Either way, you will need your parent or other responsible adult to act as as proctor. If you take the exam (or part of the exam, such as the multiple choice section) in the Moodle, you will need to complete it before it closes. If I email the exam to you, or if you take the problem section of the exam on paper, you will need to type or scan in your answers to a computer file, and upload the file to the Moodle assignment for that exams before the assignment closes.

Most exams will include a multiple-choice or other format objective section, a problem section, and a lab essay section. All sections are 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. Let me know if you need special chat times for your study group.


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.

  • Directed observation

    All observations of stars and planets, most observations of plants and animals in their native habitats, and many observations of geological specimens and meteorological events, are "field" observations. The situations must be allowed to occur without human direction, either because such direction is impossible (we can't control when a star will go nova), or because human intervention would interfer with the observation (we don't want to feed animals if we are researching their eating habits in the wild). The best we can do is make many observations of phenomena that are as similar as possible.

  • Laboratory-based experiments

    Laboratory-based observations are much more tightly controlled. Specific techniques and equipment are used for particular kinds of data collection. The experimenter can often vary only one factor at a time to see how it affects other dependencies. This allows many experimentalists to compare their results easily.

  • Surveys

    Frequently, research in one area reveals a tendency for a particular phenomena\on to behave a certain way. Rather than simply starting to observe the phenomena anew, one may choose to go back through past observations, looking for the same patterns or evidence of how nature behaved in similar circumstances. Surveys of historical data are common in weather studies, where such records exist for periods of 100 to 150 years, and in astronomical observations.

    Surveys and re-examination of chemical data are rather uncommon, since most researchers prefer to redo an experiment with questionable results.


Special concerns for Chemistry Labs

Chemistry experiments, of all the sciences we teach at Scholars Online, pose the most dangers to the students. Glass equipment, sharp edges, open and very hot flams, and chemicals that are able to burn or poison, are all hazards. The safety guide on the Science website provides a general guide, but far better is the safety information in your Illustrated Guide to Home Chemistry Experiments, and the safety information that comes with the chemicals and equipment that you may purchase. We will spend significant time on safety practices for chemists, and you will need to complete a lab safety quiz before your lab reports will count toward your grade, as well as three "skills and safety" lab exercises.


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

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 computers are really good at. The online sites we will access use 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!