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Wednesday, October 28, 2015

The One Where We All Gained Some Modeling Experience

Unit 1.B: Intramolecular Structure 

Part 2: Covalent Compounds

"What element is a girl's future best friend? Carbon."

Practice Problems:

     In this unit, the type of problem that I had the most difficulty with was when I had to apply what I knew about molecular geometry to an actual picture of a more complex compound and identify specific molecular shapes. Seeing the compound as an actual model slightly confused me since I was used to seeing compounds on paper. I understood most other practice set problems, though it did take me a while to memorize the bond angles of different molecular shapes.
Ex. of Understood Problems
Draw the Lewis structure for the the phosphate ion, PO43-.

Ex. of Challenging Problems
Shown below is the a molecular model for the neurotransmitter Serotonin. Circle a bent atom and place a square around a pyramidal atom.

     On the second day of the cycle, we were asked to predict whether methane or acetylene is more explosive. Since methane has less bonds between atoms and therefore should be "easier to separate/blow up", my group guessed that it was more explosive. We later learned that acetylene was more explosive because the triple bond between its carbon atoms has more "bond strain" and wants to break apart more than methane's single bonds. However simply learning these things just didn't do it for our class, so we got to see for ourselves just how explosive acetylene is! 

An "Irish For a Day" guest experiences methane's explosive properties firsthand

Igniting acetylene, the more explosive compound
     We were introduced to molecular geometry and learned about five different types of compound shapes. These five types were: linear, bent, triangular planar, triangular pyramidal, and tetrahedral. All these compound shapes are governed by VSEPR theory, or "valence shell electron pair repulsion".

My notes for VSEPR theory, notice the special way 3D compounds are drawn
     During this cycle we got to try and "hack" some problems taken from previous AP exams. Instead of just solving them on paper, we got to make physical models of the compounds in the problems. This gave us a unique view regarding molecular geometry problems and really helped me understand VSEPR theory more.

Two of the models we made while solving previous AP chemistry exam problems
Quiz: (To Be Edited After The Tests Get Returned)
     This cycle's second quiz required more computations in comparison to the previous one, which was one of the major factors that slowed me down. Though I prepared using both the practice set and the examples in the summary notes, the final problem (similar to the "challenging" problem mentioned above) still took me longer than I would have liked. I kept on second guessing myself and was unsure if I chose the correct central atom.

  • Regarding the exceptions to the formula for finding a compound's number of bonds, why does hydrogen only want 2 electrons and boron only want 6?

Thursday, October 15, 2015

Q1 i2 Project Benchmark


     This year, I have decided to pursue an interest that I have wanted to work on for years. Ever since being introduced to the world of microbiology through a PBS game show episode that premiered when I was 6, I have wanted to conduct some sort of research concerning this field of study. But as the years passed I believed that I would never get the opportunity to do so. Until now!

     My i2 project this year will be a combination of learning a skill and making a product that demonstrates my knowledge. Drawing most of my inspiration from the Human Microbiome Project, I will learn how to identify various types of bacteria and conduct an experiment of my own in which I will collect and identify bacteria from human samples. In terms of a tangible product, I will document this process by filming it and by making a write up summarizing my experiment. 

     After learning about the Human Microbiome Project, I suddenly recalled my first-grade self's  interest in the subject. Since then, there have been countless advancements in microbiology. A few of my favorite videos describing the human microbiome project and applications of microbiome research can be found below.

Above is a description of the HMP and how it works, from the University of Michigan Health System. This video helped me further my knowledge on the HMP and what they do.  A part of my goal is to be able to understand most of the complex terms included in this video as well as the HMP website.

A short, interesting video that reveals the connection between dogs and human microbiomes, from the Argonne National Laboratory, Illinois, included above. It describes an interesting relationship that I was not previously aware of and one that I might integrate into my experiment.

A video courtesy of the Argonne National Lab describing fascinating research connecting the human microbiome and food allergies is found above. Just as the previous video, this shows an aspect of microbiology that I may want to pursue in my experiment.


Actions (filming will take place during nearly all these steps)
Begin planning research opportunities and finding resources that can help me achieve my goal
      ex. contact adults that can provide leads and/or act as mentors;                       preferably in the microbiology field
Finalize my "game plan" and who/what will assist me in my project
      ex. come up with project plan and schedule
Begin research using mainly print sources
     ex. borrow most sources from libraries; take notes 
Continue my research over the break/begin planning experiment*
Finish research and begin conceptualizing/conducting experiment 
Begin experiment 
Continue experiment
Complete experiment, do write up and compile/edit footage
Finalize my presentation (write up/video) 

*subject pending, since it is dependent on my research

     My long term plan is to build up to being involved in bioinformatics. This year, I will work on the "bio" part. If all goes well, I would like to continue this project next year as a junior by learning how to code. This would fulfill the "informatics" portion by bridging my research from this year and the coding skills I will learn as a junior. 

Sunday, October 11, 2015

The One Where We Explode A Gummy Bear

Unit 1.B: Intramolecular Structure 

Part 1: Ionic Compounds

"If H2O is water and H2O2 is hydrogen peroxide, what's H2O4?  

Practice Problems:

     Problems that involved Electron Configuration were a little confusing at first, but once I got used to reading the chart I was able to solve them quickly. It was the same with Lewis Structure mechanisms, once I understood how atoms with different levels of electronegativity formed different compounds I could quickly draw the mechanisms. What challenged me the most were problems that asked for the formula of a certain compound. I tended to rush and just use the shortcut instead of actually thinking about the number of valence electrons each element had and how this affected the formula.
Ex. of Understood Problems

Provide the Electron Configuration for iron, Fe.
Iron (Fe) 1s22s22p63s23p64s23d6
Ex. of Challenging Problems

Provide Ionic Compound formula for Carbon Dioxide.
CO2  (NOT C2O4)
     We constructed our own conductivity probes and tested various things around the room to see if they were conductive. After, we were given two different compounds, AB and CD. We then tested each to see which one would be conductive as an aqueous solution (dissolved in water) and find out why this happened.

 Our conductivity probe
Testing compound AB as an aqueous solution
     My group agreed that in water, whatever held compound AB disappeared, which allowed the electrons from the conductivity probe to pass through and form a complete circuit. In compound CD, water had little to no effect on the bond formed by CD and this bond meant that electrons weren't able to pass through the solution and form a complete circuit. We later learned that AB was an ionic compound and CS was a covalent one. 

Our model showing our visual observations and explanation AB's conductivity as an aqueous solution
     Another activity we did was observe the reaction that occurred when alkali metals with very low electronegativity levels were placed in water. 

As you can see, the experiment was a "blast"! 
     An interesting experiment we held was a mystery compound identification in which we had 4 unknown compounds and list of 4 compounds that each could be. To identify which was which, we had to mix each compound with another and observe the reaction. I really enjoyed how this activity integrated logic with chemistry concepts.

The petri dish where we conducted our tests
     An activity that deserves an honorable mention was one that we did near the beginning of the cycle. After learning that gummy bears were mostly made of carbon, we found that it would behave similarly to our bodies when put in a certain heated chemical compound. 

Needless to say, we got a lot of curious stares as we conducted this experiment in the courtyard. Poor gummy bear.
      Since the skills needed for this cycle involved a lot of drawing, I went through the practice problems provided in both the Google Doc and the video to prepare for the cycle test. On the test, I thought it was interesting that we were given an element X and element Y and had to guess what each could be. It made me think more than if I simply had to provide Lewis Structure mechanisms for any two elements. The chart at the end of the test had one problem that confused me. In this problem, we were given manganese and oxygen. As a transition metal, Manganese had a roman numeral to indicate its charge. I was surprised when I saw that it had a charge of 5+, since I thought that the charge would always refer to a low electronegativity. Next time, I'll check my answers at least once since I could have easily written the wrong subscript for any of the formula.  I'll also try to explain things more clearly for the short answer portion.
  • Are there any other differences between ionic and covalent compounds that we can test?
  • I'd like to learn a bit more about the s, p, d, f subshells.