Reading
Notes for Chapter 01
These are Dr. Bodwin's reading notes for Chapter 01 of "Chemistry 2e" from OpenStax. I am using a local .pdf
copy that was downloaded in May 2020.
Chapter
Summary:
What exactly is "chemistry"? This chapter aims to set the table for our
semester or year of studying chemistry. People often treat first chapters as
throw-away material, but it is important to take this chapter seriously to
get familiar with the format and style of the book as well as the most
fundamental tools we will use in our study.
What is
"chemistry":
One of my favorite college professors defined chemistry as "stuff changes
into other stuff".
Chemistry is the study of matter and its changes.
I often find it helpful to think about different science disciplines in
terms of how they balance theory and application. Chemistry tends to be a
little less theoretical than
physics, and a little more
theoretical than biology or engineering. That's not an absolute truth, and
it doesn't make any of those fields better or worse, it's just a way to
frame our approach.
Nature of
Science/Scientific Approach/Scientific Method:
The key to all science is curiosity. Whenever you see something happening,
it should be pretty natural to wonder "Why?"
The way I think about the "scientific method" is something like this... and
I'll tell it like a story:
The other day, I did a thing. When I saw
what happened, I thought, "Huh, that's weird. I wonder why it did that?
Maybe it did that because of this." So I did the thing again to see what
would happen the next time. And it did the same thing. I tried it a few
more times just to be sure, but it looks like my explanation might make
sense. My friend tried to do the same thing, and she saw the same thing
happen. We asked a lot of other people, and it looks like every time some
does that thing, they see the same thing happen. A bunch of the other
people thought my explanation made sense and when they did the thing it
seemed to match my explanation, so we're pretty sure we're right, but we
should probably continue to check out what happens when we do the thing
and adjust our explanation if we need to.
Translating that into "science" words...
The other day, I did a thing. (Observation)
When I saw what happened, I thought, "Huh, that's weird. I wonder why it
did that? Maybe it did that because of this." (Hypothesis)
So I did the thing again to see what would happen the next time. (Experiment)
And it did the same thing. I tried it a few more times just to be sure (Repeat
Experiments, Make Predictions), but it looks like my explanation
might make sense. My friend tried to do the same thing, and she saw the
same thing happen. We asked a lot of other people, and it looks like every
time some does that thing, they see the same thing happen. (Law)
A bunch of the other people thought my explanation made sense and when
they did the thing it seemed to match my explanation, so we're pretty sure
we're right, but we should probably continue to check out what happens
when we do the thing and adjust our explanation if we need to. (Theory)
States of
Matter:
States of matter is actually a topic we will re-visit a number of times
throughout the course. Depending what we are trying to explain, we will need
definitions of different precision or focus. The "how matter interacts with
its container" definitions are a good place for us to start.
"Matter" is something that has mass and occupies space.
Pay attention to the distinction between "mass" and "weight". Mass measures
the amount of a substance; weight measures how matter is affected by gravity
and its medium.
The Law of Conservation of Matter can be stated a few different ways (just
like the definitions of the states of matter). Probably the most basic ways
is "matter cannot be created or destroyed". We'll look at a few cases where
that simple definition isn't exactly true, but it's a good place to start.
One of the best ways to figure out the distinction between elements,
compounds, and mixtures is to just observe things around you. Look for
examples and test your examples. You're a scientist, afterall.
Physical and
Chemical Properties and Changes:
Why are we studying "physical" changes in a chemistry course?
Extensive vs Intensive properties are important... What weighs more: a
kilogram of lead or a kilogram of feathers?
The NFPA hazard diamond appears in a LOT of places. Once you start looking
for it, you'll see it. To help remember what which part means what, these
are sometimes called "heifer diamonds" because the top 3 squares are "H-F-R"
for "health", "fire", and "reactivity".
Measurements
and Math:
There are a lot of different things we can measure. I will typically give
you conversion factors, but there are some that I will expect you to be able
to do without a conversion factor, most notably metric/SI prefix
conversions. You shouldn't need to write out a big, complex mathematical
equation to convert milliliters to liters or meters to centimeters...
practice these and they will become much easier to work through.
Accuracy and precision are BOTH important. Accuracy can often be improved
with practice, precision is usually improved with changes to an experiment.
Significant Figures (sigfigs) are important because they give us information
about the uncertainty of a number. They take practice. But remember, sigfigs
are not just some meaningless thing that chemistry professors obsess over,
they are important because they tell us how reliable a measurement is. Sig
Figs Slides
I will be evaluating sigfigs in any numerical answers you provide in your
assignments for this class.
I am a HUGE proponent of dimensional analysis. If you pay attention to units
on every number you use, you will make FAR fewer errors, and you will even
be able to do some problems that you've never seen before just by following
the dimensional analysis.
"Conversion factors" are just relationships between 2 different descriptions
of the same quantity. Use dimensional analysis to figure out how use them.
Temperature conversions are excellent examples of learning a process
rather than just memorizing a formula.
The book derives formulas, but make sure you look at the process being used.
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