Continuation on Electron Pairs and Start of Hybridization

To start off class today, we first discussed the types and names of the electron pairs we learned yesterday (In Ethan's Post). Next, we moved into looking at 4,5, and 6 areas of concentration. These are the highest levels of concentration that can ever happen in an atom.

The first molecule that we looked at for the day was PF5. PF5 has 40 valence electrons and using this, we constructed the Lewis structure. Phosphorus can break the octet rule, which is the only reason why this Lewis Structure works. Then we used that to help us form the angles at which the balloons in the demonstration were forming(90,120,180). PF5 is an example of a trigonal bipyramid molecule. We then did the same steps for the Octahedron molecule of SF6. Sulfur can also break the octet rule.

During the demonstrations of the shapes of how these molecules would look like if they were much bigger, we also saw how the non-bonding pairs of atoms continuously took away an equatorial angle, instead of a linear angle. This happens because this is the most stable configuration.

The Last thing we learned about for the day was hybridization. Hybridization is the mixing of one s orbital and one p orbital in order to produce two sp orbitals. We looked at a video that explained the different formations as well as the actual action of what it would look like. . That is all we learned.

The next scribe is...Deena M.

Insolubility and Solubility

Mr. Liberman started off class today by first reviewing the rules of solubility and insolubility. First off, we restated what those words mean: something is soluble if it is able to dissolve in water, and something is insoluble if a precipitate forms in water. Then Mr. Lieberman explained that the lab that we did yesterday was the basis on which we were eventually going to base the solubility of certain compounds off of. This will include compounds that are commonly found around us and whether they are soluble or not, but it is not that black and white. There are some compounds such as silicate (SiO3) that is insoluble unless it contains the ions of K+ and Na+. There are many more examples like this.

To make things more interesting, Mr. Lieberman did the Lead Iodide experiment to show that certain compounds are always soluble (NO3), and therefore, you are able to identify the solids in a reaction. See Video Below:

This reaction is of Lead and Iodine. This solid had to form between these two elements because NO3(nitrate) mixed with any other element is soluble.

Since Lieberman was in a good mood, after explaining all of this, he let us work on the lab and the worksheets we got. Everybody was working until the bell rang and class ended. That was it for the day. The next scribe is....

Kaitlin S.

Chapter 3 Introduction Including Dimensional Analysis

Today in class we started off with talking about what would be on the test tomorrow. It will be similar to the first one: 35 multiple choice questions and then two show-your-work problems at the end of the test. Overall, the test will be worth around 80 points or a little more.

After wrapping up the discussion, we jumped into unit three, which was what today's lesson was about. We were introduced to the dimensional analysis method of conversion, which is quite simple, but will come in handy if you know it well now. So, make sure that you pay close attention in class for he next few days!! This method deals with multiplication and division for converting large numbers, or small numbers, into different units of measurement.

Dimensional Analysis uses what are called conversion factors. In the notes, the example was 12 donuts/1 dozen. We then took the next step and did a few sample problems. I will go over one of the ones gone over in class:

1) How many donuts are in 3.5 dozen?

--First, you should start with what you know/given. (3.5 dozen)

--Then, align the conversion factor so that the units cancel out and you are left with the ones you want. (12 donuts/1 dozen)

3.5 dozen x 12 donuts/1 dozen = 42 donuts

Since the units are dozen and it is both in the numerator and the denominator of the problem, they cancel out. You are then left with only the unit of donuts, all that is left to do is multiply 3.5 and 12. Now, the thing to keep in mind that really helps when setting up the problem is to underline the variables and pick out what values the word problem gives you. Also, even though this is a problem that is easily done in your head, when we start dealing with larger numbers and units that you may or may not be familiar with, knowing this method will make your life much easier. Another thing to remember is that when using the calculator to multiply and divide it IS IMPORTANT THAT YOU TYPE THE EQUATION IN AS SEEN, otherwise the answer will not be correct.

Mr. Lieberman went over a few more problems with the class so that we started to get the idea of this new concept and then he explained a worksheet that we picked up at the beginning of the class. It dealt with the same concepts that we worked with in class. So, for the last 15 minutes, people spent their time getting used to the method.

As everybody started to pack up, the bell rang and another day in chemistry was gone.

The next scribe is Kaitlin Y.