Week Many: Versace Versace This Class is Exhausting

This week's theme was enthalpy. Or entropy. I'm not sure. Both? Hmmmmm...
Just kidding. That was a joke. Ha ha.
My week started out doing the lab from last week. I was instrumental to the team effort, not so much with my vast understanding of anything going on but rather with problem-solving skills, such as noting that the blue solutions must contain copper. It was a useful activity in that we had a real-life experience with precipitates instead of just hearing about them. Precipitation reactions take place when two solutions, usually of ionic compounds, react together. Not all of it may dissolve and the reaction of the non-solubles produces solid matter. It looks really cool.

We've also covered a boatload of stuff under the "thermodynamics" category. First of all: energy can be defined as the ability to change or to do werk. I mean work. Enthalpy! is the measure of all the energy in a system. Exothermic reactions have negative enthalpy values while endothermic reactions are positive. Entropy is a different thing. Which gets confusing. It is basically how messy something is (at the molecular level).

The ways we learn things is the same. We do lectures at home and whiteboard problems at school. However, I think that for such a confusing topic as thermodynamics, lectures are not helpful. You cannot ask a lecture a question.

I have no jokes today.

Week 7: Use The Force, Larkin

Let's talk prefixes. What's the difference between an intermolecular force and an intramolecular force? Inter means between or among. Intra means inside or within. So an intramolecular force is one within a molecule, and an intermolecular force is between two molecules. Latin for the win!

Intermolecular forces can determine many properties of substances, such as boiling point and dissolubility. The three types of intermolecular forces are as follows: London dispersion forces, dipole-dipole forces, and hydrogen bonds. Let's take a more in-depth gander at these.

A London dispersion force occurs because there is a temporary concentration of electrons on one side of an atom which causes an artificial dipole in the molecule. This can occur in all molecules. It is also known as the induced dipole-induced dipole force. 

A similar force is the dipole-dipole force. The partial charges on the molecules create an attraction that is roughly the same strength as the London dispersion force. This does not occur in all molecules, only ones that naturally have dipoles.

But the strongest intermolecular force is... Hydrogen bonding!

Here's a nice little visual.

A hydrogen bond is an attraction that occurs between a hydrogen atom and either a fluorine, oxygen, or nitrogen atom. We tackled these in the IMF worksheets we did this week.

The other thing we did this week was learn how things dissolve (in water) by way of POGIL. Take the common example of dissolving table salt, or sodium chloride, in water. The ionic bond between sodium and chlorine is weaker than the hydrogen bonds that occur between water and the sodium and chlorine, so the ionic bond breaks apart. This successfully dissolves the salt into the water (see diagram below).

In summary, we needed to have a knowledge base about IMFs in order to move on to other subjects relating to it, like dissolving things and boiling points and such. This is important so we know what we're doing for future subjects. 

I have no jokes for this week. It was humorous in no ways. Forgive me.

I've Lost Count of How Many Weeks it's Been

I cannot speak very heavily on any subject in particular regarding this week; it was a mixed bag of varied things. I guess I should give a day-by-day account of what we did.
On Monday, we did a lot of test review on molecular shapes, Lewis structures, VSEPR and the like. I think that the stuff that I was most worried about, I ended up understanding better than the stuff I felt like I had down pat. Alas, I must learn to review more effectively.
On Tuesday, we took the test. I was able to finish it all this time! I felt really good about my short response and solid on multiple choice. These turned out to be pretty accurate when reflected in my grade. Overall, I really liked this unit.
Wednesday:

(Yes, that's a mole cookie.)

And that pretty much sums up Wednesday.

Oh, and we also wrote essays on polarity that had to do with paintballs. This wasn't very hard in my opinion, but it was really kind of vague. Also, seeing as none of us had written an essay in a science class, it was pretty awkward. But anyways, here is my essay if you have any interest in paintball chemistry.

Thursday, we took a practice AP exam (multiple choice). I actually apparently scored rather well. Obviously there was a lot of stuff I didn't know, but I'm kind of excited to learn the rest of it in the upcoming months.

On Friday, we started learning things again. We did some POGILs on metals and ionic bonds. Basic difference between ionic bonds and covalent bonds: covalent bonds involve the sharing of electrons between two atoms, whereas ionic bonds are when one of the two atoms sacrifices one of its electrons and gives it to the other. Metals, as they form cations, usually form ionic bonds with anions and if there are two nonmetals, they usually form a covalent bond. 

That's all for this very exciting/bizarre week!

(Also I have another mole day joke.

What did Avogadro yell at the Battle of San Jacinto?

Remember the Alamole!)

Week 5: Pumpkins and Mozart

Soundtrack for the week!

Here's a thought: Why isn't VSEPR pronounced vuh-seh-pur instead?

We kicked off the week by making more models. But instead of making electron-domain balloon models like this...

We made toothpick and gumdrop models like this. 

This was the second half of the VSEPR packet that we did. These models show the molecular geometry, which usually looks different from the electron domain geometry. They look so different because the balloon models show where each electron is likely (LIKELY) to be at any given moment. The gumdrop models show more the angles at which each atom is bonded to the central atom. The central atom isn't visible in the electron domain geometry, but it is visible in molecular geometry. The biggest difference is that molecular geometry models only physically show the electrons that exist in bonds, while electron domain geometry models also show nonbonded valence electrons. The point of this exercise was to make us have to actively think and work on how these models work with each other, rather than only having us do the lectures (which can get hypnotic and bland at times). As Dr. Finnan seems to think, others' failure is an excellent way to learn. Which is true.
In my understanding, the main idea of VSEPR is that the electrons and protons within each molecule naturally repel each other and attract each other. This makes them settle into certain shapes to be the least repellent and volatile. Kind of how the balloons settle to have the least friction.
Other things we did this week:

• Formal charges. Formula for calculating formal charge: FC = V - N - (B/2). You put the formal charge in the Lewis structure, then add them all up for the molecule. You always want the structure with the lowest charges, because it's more correct. 
• Hypervalency (and electron deficiency). Hypervalency is when a central atom holds more than eight valence electrons. This can only happen in periods 3-7 on the periodic table. 
  
  Phosphorus pentachloride, pictured above, is a prime example. Boron and beryllium may be electron deficient, given their number of orbitals. 
  
  
  Weekly chemistry joke: Helium walks into a bar and orders a drink. The bartender curses and yells "We don't serve noble gases here!"
  Helium doesn't react.
  Ba-dum-chhhh. 
  
  

Week 4: I learned how to tie a balloon!

This week has been my favorite week so far. We've learned a good deal through a variety of activities. We did quite a few POGILs, a lab, and some modeling activities.
The lab this week was dealing with the concentration of copper in a solution and how it relates to absorbency. I was unfortunately absent for Wednesday and missed the fun reactions (and truthfully I'm still a little confused as to what's going on). But the group that I'm in did the correlation curve instead of the visual, which I enjoy doing because I think colorimeters are fun. This lab is kind of similar to our first lab.
Labs make this class so much better. I often sit in math class and think to myself, why am I learning this when I know I'll never use it in real life? I think that if we did no labs and just did POGILs and worksheets all year this class would take on a similar effect. Thankfully, we do other things which makes this a rather lively course.
We also started an activity where we made balloons into molecules in order to better visualize what they actually look like. This involves blowing up and twisting together red and white balloons (symbolizing electron clouds). This is a really good way of teaching us materials, as we're more excited about participating and we have to understand the concept in order to finish it. We haven't yet finished this activity, but I believe we're also going to make models out of toothpicks and gumdrops. I think the purpose of this activity is to get us to understand that Lewis models, despite their undebatable usefulness, aren't actually visually accurate. I imagine that this might have been a common misconception. I was searching the internet for "balloon molecules" and I found a very different approach to making balloon models using long balloons. This seems like a cool idea.

On the homework front, we've been doing tons of lecture quizzes, which I enjoy. I usually watch them all twice, so I can get a better idea of the whole picture instead of little chunks only. I also like that the questions make me think about the concepts rather than just doing work.
For your weekly science meme, Chemistry Cat is back!

Week 3: Hot Pots and Lewis Dots

This week was kind of split into two parts. The first part was focused on the test we took Wednesday. The second part we started on some new material, which I greatly appreciated.
To be blunt, I did very poorly on the test. In hindsight, I should've practiced more for the short response than I did for the multiple choice, because even if I didn't have a calculator I felt I knew the concepts well enough. But for the short response I had severe technical difficulties. This is a problem that I need to work hard to address. But I thought the Hot Pot quizzes were very helpful with the multiple choice section. I'd like to have more of those before tests in the future.
I must admit that I jumped for joy when Dr. Finnan said that there wouldn't really be any math on the next test.
For the remainder of the week, we began doing Lewis dot diagrams which I think are really cute and fun to draw. These are diagrams that show how many valence electrons any given atom has and you can put them together to form molecules. Here is the diagram for water, which I think looks rather like two tie fighters circling the Death Star.

This shows that one atom of oxygen has 6 valence electrons and can thus form bonds with two hydrogen atoms (which have 1 valence electron each). The dots stand for valence electrons. The dashes that you can see are just an easier way to write two dots shared between a pair of atoms. 

Another new thing we discussed was the "octet rule" which basically states that each atom's greatest life ambition is to have 8 valence electrons and will drop or gain electrons in order to do so. This doesn't apply to all elements though, such as hydrogen, which follows a similar "duet rule". 

I think the most confusing thing for most people right now is probably understanding the difference between valence electrons and total electrons. I imagine that in the next few days this will no longer be a problem. 

Rumor has it that we will have a lab next week, which I am incredibly excited for given how entertaining the last one was. I'll leave you all with your science meme of the week. 

Week 2: Let's Do Some Math (!)

Coming off of last week, when we did this really fun lab about molarity, this week was pretty mellow. The majority of it was spent doing worksheets at home and POGILs during class. I'd say that the main theme of this week was "calculations". We did a billion more stoichiometry worksheets. We also started in on some empirical formulas, which I think are much more tolerable than the straight stoich worksheets.
This week I feel like I really gained a better understanding of how to use the different formulas, though.  The repetition of them what with the worksheets and the in-class work kind of forced me to sit down and really work through and get it locked down.
All the stoichiometry did kind of get my brain back into math-mode, which is new since I don't have a math class this trimester. I wonder how much of chemistry is going to be what I call "straight math"? Only time will tell.
For me, the fun (ha ha) part of the week was starting on the empirical formulas. I really enjoy learning new concepts, especially when we'd been battling stoich for the second week now. Here's a cute graphic I found that I think accurately explains the main idea of empirical formulas:

I really like this image because often times it's easier to get the idea of certain things with non-chemistry analogies (like the egg POGIL we did in week 1). It can be tempting at first to just copy down the work from the lectures or the whiteboards, but this isn't a good idea. Later on, having a solid knowledge of the actual idea comes in handy. 

I can't help but wonder how much I'll have to use this stuff as the course goes on. Part of me hopes that it'll be gone soon but I also think that it's just kind of a basic skill I'll have to get really good at. 

I guess that means the hard stuff is yet to come! What fun! Next week I really hope we have a lab or something because it makes the blog post a lot more interesting. 

For a closing thought, here's a lovely picture of the cherished Chemistry Cat that pretty much sums up my feelings of this week.