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.
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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