Chemistry—Semester A

The original chemical romance.

  • Credit Recovery Enabled
  • Course Length: 18 weeks
  • Course Type: Basic
  • Category:
    • Science
    • High School

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Shmoop's Chemistry course has been granted a-g certification, which means it has met the rigorous iNACOL Standards for Quality Online Courses and will now be honored as part of the requirements for admission into the University of California system.

This course has also been certified by Quality Matters, a trusted quality assurance organization that provides course review services to certify the quality of online and blended courses.


Now, what's hot, what's not?
Tell us who's Bohr, why Lewis sells out in the stores?
You tell us who flopped, who copped the photons?
Whose solids got form?
Who's mostly neg down the atom?

These are questions we'll explore as we question everything we know about chemistry. Chemistry evolved from alchemy, and even though we study it with a bit more scientific rigor than alchemists did, a little of the magical still lingers. If anything about studying smelly sulfur compounds isn't magical, we don't know what magical is.

In this course, we'll talk about:

  • the basics of lab safety—because nobody wants to lose an eye, ear, or leg.
  • what's the matter with matter, in all its different phases and forms.
  • what makes certain atoms join certain clubs that become certain compounds...but certainly not other compounds.
  • why chemists across the world keep a Periodic Table of the Elements with them at all times.
  • how elements play with light to make fireworks and auroras.

Our chemistry lessons—chock full of glossaries, readings, and activities—are tagged with the Next Generation Science Standards (NGSS), so you can make chemistry answer all your questions.

P.S. This is Semester A of a two-semester course. To check out Semester B, clicky-click here.

Required Skills

Knowledge of Algebra concepts


Unit Breakdown

1 Chemistry—Semester A - Conducting Investigations in Chemistry

We'll start this course off right, by laying down the law on the dos and don'ts of chemistry. Always wearing your goggles, designing scientific experiments, carefully measuring your data, and presenting your analysis in a clear way? All dos. Roasting marshmallows with the Bunsen burner? That's a don't.

2 Chemistry—Semester A - Making Measurements and Calculations in Chemistry

This wouldn't be a science course if we weren't taking measurements. Might as well make sure we know what we're doing there, right? That includes using those foreign-looking metric units that everybody else on the planet is so in love with.

3 Chemistry—Semester A - Matter

Here is where we'll learn what the matter with matter is. What it is, what it does, and what it doesn't—it's all on the agenda. This whole course is about matter, so we might as well know what we're dealing with here.

4 Chemistry—Semester A - Atoms

Small things are cute. It's just a fact of life—puppies, baby koalas, Knut, undersized hats: all cute. That means that atoms are just about the cutest things around, except for the subatomic particles that make them up. You'll need to brace yourself for a cuteness overload in this unit, as we delve into the tiny mysteries of these wee-tiny particles.

5 Chemistry—Semester A - The Periodic Table

When it comes to famous tables, the Periodic Table has pretty much zero competition. What other table can compete with describing every element in existence, and in enough detail to satisfy even the nosiest snoop? In this unit, we'll give you the inside scoop on how to get on this table's good side.

6 Chemistry—Semester A - Electrons

We'll be learning about the little negative particles that could in this unit. By spending some bonding time with Lewis, Bohr, Planck, and ol' Albert E, we'll get the skinny on the voodoo that electrons do.

7 Chemistry—Semester A - Chemical Bonds

Speaking of bonding, that's what this unit is all about. And speaking of electrons, that's what bonding is all about. We'll cover the rules for atoms joining up, along with what you call these new molecules. Look out, Filliam H. Muffman—there are some new celebrity couples in town.

8 Chemistry—Semester A - Chemistry Meets Geometry

Molecules aren't something that we just made up: they're real things. And that means they exist in the real world, in 3D space. Those tiny, can't-even-see-them particles have a shape, and it'll be important to know what it is for each molecule. We'll pass along the secret to predicting their shape in this unit.

9 Chemistry—Semester A - Forces of Attraction

Elmer's doesn't sell a glue that's small enough to work on individual atoms (probably because glue is made of atoms), so how do atoms stick together in molecules? And how do molecules interact with each other? The answers are "intra- and intermolecular forces," o' course. We'll cap off this semester by getting our hands all over these forces and seeing what sticks.


Recommended prerequisites:

  • Algebra I—Semester A
  • Algebra I—Semester B

  • Sample Lesson - Introduction

    Lesson 4.02: Subatomic Particles

    If you think atoms are small, prepare to have your mind blown. We’re getting even smaller in this lesson on subatomic particles. That’s right, we said subatomic. The Latin prefix means “beneath” or “under,” and we’re going to do just that and delve under the hood to see what atoms made of.

    We’ve mentioned the parts that make atoms run before: they’re known on the street as protons, neutrons, and electrons. They’re sort of like the engine, transmission, and drivetrain of a car—but less greasy, and they get way better gas mileage. In fact, now that we think about it, they aren’t anything like an engine, transmission, or drivetrain.

     

    "Well, how in tarnation did I end up with an extra proton?" (Source)

    The important questions here are, “what’s the purpose of protons, neutrons, and electrons?” And “why do we care about them when we can’t even see them?”

    We are going to answer both of those questions, plus address things like:

    “If electrons are constantly moving, what keeps them from just flying off an atom, like the spare tire did on the highway that one time Papa Shmoop tried to fix a flat?”

    “If there are protons, neutrons, and electrons inside an atom, is there anything inside those particles?”

    Throw on your coveralls and grab your monkey wrench, because we’re about to find out.


    Sample Lesson - Reading

    Reading 4.4.02: Shmoop’s Gone Subatomic

    He Lost His Amateur Status, and Now He’s a Proton

    Luckily, we’ve already learned a bit about the three basic subatomic particles when we were talking about Thomson, Rutherford, and Chadwick—those gents who discovered the electron, proton, and neutron, respectively. The vast majority of atoms are comprised of these three subatomic particles.

    The proton hangs out in the nucleus of the atom. As we learned earlier, protons carry a positive charge, a +1 atomic charge to be precise. The number of protons also dictates the atomic number for an element. So if we’re dealing with a 1-proton atom, we have the element with an atomic number of 1: hydrogen. Got a 2-proton atom? Then it’s helium. An 894-proton atom? Well, that last one doesn’t exist, as far as we know. If you come across that one, students fifty years from now will be reading about you right along with Dalton and Bohr, so keep your eyes open.

    There's one last thing we need to note about the proton, and that’s its mass. A proton has a mass of 1.6726 × 10-24 grams. In case you can’t tell, that’s a really tiny number—not exactly a mass you can measure with your bathroom scale, and it’s a total pain to write out, too. That’s why scientists came up with an easier unit for us to work with, known as the atomic mass unit (abbreviated as AMU or amu). A proton has an AMU of 1.0073.

    We know, we know! You’re asking yourself why all the sig-figs—why not make things easier and say a proton has an AMU of 1? That would be easier, but you didn’t expect chemistry to be that simple, did you? We’ll talk about this a bit more later in the unit, but the short answer is that the AMU is a relative unit that is based on the mass of Carbon-12, and the calculation worked out to be close to, but not quite, 1 AMU.

    Neutrons: The Switzerland of the Subatomic World

    Chillin’ alongside the protons in the nucleus is our next subatomic particle, the neutron. Unlike the proton, the neutron carries no electrical charge. It’s similar to the proton, though, in that it contributes to the mass of the atom. Care to guess the mass of a neutron?

    If you guessed 1.0073 AMUs, you’re actually pretty close. Unfortunately, you’re also a little off. Neutrons actually have a mass of 1.0078 AMUs. Go figure. Maybe since neutrons don’t carry around a charge, they figure they can put on a few extra pounds.

    Electrons Are Always Soooo Negative

    Electrons are sort of the outcasts in the subatomic world. While the protons and neutrons are being all chill in the nucleus, the electrons are off in the distance, frenetically whizzing around in circles. We learned about Bohr’s planetary model in the last lesson, and that’s not a bad way to visualize what electrons are doing, cruising around the nucleus like planets around the Sun.

    In reality, though, the electrons are moving way too fast to ever pinpoint where exactly they are. On top of that, they can change their distance from the nucleus, depending on how much energy they have. That’s why modern scientists use the Electron Cloud model instead. The electron cloud is a region surrounding the nucleus where the electron(s) might inhabit.

    A helium atom surrounded by an electron cloud.
    A depiction of an electron cloud for a helium atom. The darker the yellow, the more likely the electrons are to be there.

    The reason those zippy little electrons don’t just fly off into space is that they have a negative charge, and so they’re attracted to the positively charged protons in the nucleus. In fact, electrons and protons make quite the pair. Protons have a +1 charge and electrons have a -1 charge. Finally, whole numbers again, right?

    Don’t get too happy with yourself, though, because as you could probably guess, the mass of an electron can’t possibly be a whole number. In fact, it’s not even close to a whole number, at 0.00054858 AMUs. That’s a really, reeeeeeeally small number—so small that scientists consider the mass of electrons to be negligible, and don’t include them when considering the atomic mass of an element.

    However, electrons do factor into one other aspect of an atom’s characteristics, and that is its reactivity. Some atoms are prone to losing electrons to either form bonds or become positively charged ions. Other atoms are prone to adding electrons to either form bonds or become negatively charged ions. Then, there are the atoms that are content just the way they are. We’ll learn more about these trends later. For now, just remember that the number of electrons dictates an element’s reactivity.

    The UC Davis ChemWiki page on subatomic particles has a super helpful chart that compares the masses of the three major subatomic particles, as well as their atomic charge. You’d be helping yourself out if you got a good look at this. Hint, hint.

    May the Quark Be With You!

    Atoms are made up of protons, neutrons, and electrons. Got it. Not too complicated, right? Eh, not quite. Once scientists had the technology to build telescopes and instruments that could detect and measure the particles that were flying around in outer space, they made some interesting discoveries.

    Sure there were some of the usual suspects, like alpha particles (which are basically naked helium atoms without their electrons), but scientists also detected particles that were smaller than the basic subatomic particles. And they had weird charges, too, like -1/3 and +2/3. The scientists were pretty much like us, saying, “Gah, why fractions!? We finally had simple whole numbers to deal with.”

    Murray Gell-Mann, a theoretical physicist, came up with the idea of quarks to explain what scientists were seeing. The idea was that protons and neutrons were made up of these smaller particles that had fractional charges.

    The Crash Course

    Scientists were able to test and validate the quark theory by using particle accelerators, which are essentially giant crash courses for subatomic particles. Scientists get subatomic particles racing around on these tracks that are sometimes miles long, up to nearly the speed of light, and then they crash them into each other to see if they break up into smaller pieces.

    A particle accelerator tunnel at CERN in Geneva, Switzerland.
    “On your marks, get set, go!” (Source)

    In this manner, scientists were able to figure out that there are two fundamental subatomic particles: quarks and leptons. An electron is itself a lepton, so it can’t be broken down into smaller pieces. Protons and neutrons, on the other hand, are made up of quarks.

    These quarks come in six flavors: up, down, charm, strange, top, and bottom. That’s a descriptive and easily understood set of names, ain’t it? The two quarks that are relevant to our discussion are up and down quarks.

    Up quarks have +2/3 charge, while down quarks have a -1/3. Stick a combination of three of these quirky quarks together and you get either a proton or a neutron, and those fractions add up to whole numbers. Let’s see the math.

    A proton is made up of 2 up quarks and 1 down quark: 2/3 + 2/3 – 1/3 = 1.

    A neutron is made up of 1 up quark and 2 down quarks: 2/3 – 1/3 – 1/3 = 0.

    Either combination of flavors looks delicious to us! Sorry...we couldn’t help ourselves.

    If you really want your mind blown, check out this optional reading from the University of Oregon. It goes into more depth about quarks and leptons and the force that holds the nucleus together.


    Sample Lesson - Activity

    Activity 4.02a: Questioning Quarks

    Go pop some popcorn, because it’s movie time again. Since we can’t exactly look at atoms under a magnifying glass, we’re going to have you watch this video on how they are arranged and what keeps the electrons well behaved. Once you’re done watching the video, you’ll be ready to complete the table on this activity sheet.

    That’s not all, though; there’s a couple questions to answer below the table.

    Once you’ve filled out the activity sheet, scan or take a picture of your work and upload it using the button below.


    Sample Lesson - Activity

    1. Which subatomic particle is positively charged?

    2. Arrange the following in order from smallest to largest (in terms of their relative masses).

    3. What particle(s) is/are found inside the nucleus of the atom?

    4. Choose the correct terms to complete this statement:
      “Most of the atom’s mass is located in the __________ of the atom, while most of the atom’s volume is __________.”

    5. What “flavors” of quarks make up a proton, and how many of each are in a proton?