Wednesday, January 26, 2011

Announcements : -If you have any questions about moles find Mr. Paek ( he is free 5th and 6th period.) This is a really important unit and if you want to do good on the test you have to do good on the quizzes.

-Make sure to show all work and units in homework and quizzes, because it will get very confusing later on if you don't get in the habit of doing it right now.

- Buy a notebook if you haven't already.

- First quiz tomorrow/ 7 quizzes total this unit.

Homework: -pages 7-8.

Body: Today in class we went over some problems from pages 1-6.(Again: make sure that you go get help from the TLC or Mr. Paek if you don't get something.) Then we did a lab called: Moles Stations Lab. The lab had 9 stations, and in each one of them we calculated either the mass number, mole, or the number of atoms.

Set1: had to count the number of pairs of shoes in the room.

Set2:find the mass of Aluminum foil and find its mass number and how many moles it had.

Set3:find the mass of a carbon rod find mass number of it and how moles, then how many atoms.

Set 4:we had to find how many moles of Krypton in a graduated cylinder, and the mass of it.

Set 5:we had to find the mass of H2O, and the number of grams in one mole of H2O.

Set 6:find one mole of HCl, the number of moles in it, and the number of molecules.

Set 7:found the volume of an aluminum bar its density and the number of moles and atoms.

Set 8:find the mass if neon, and the number of atoms in it.

Set 9:find the mass of a balloon and the balloon's mole.

***examples from some problems in the lab:***

set 2: 1)The mass of Aluminum foil=3.74g

2) The mass from the periodic table = 27 g/mole

3)Number of moles Aluminum foil has=3.74 g Al foil*1mole/27g of Al foil=0.14 moles of Al.

set3: 1) Mass of carbon rod= 4.35 g

2)Mass from periodic table= 12 g/mole

3)Number of mole in this carbon rod= 4.35g carbon rod* 1mole/12 g carbon rod=.36moles

4)Number of atoms in rod=.36mol*6.02E23atoms of carbon/1mole=2.16E24 atoms of carbon

Monday, November15, 2010

11/15/2010

Announcements:

-Test will be on Wednesday after thanksgiving break.

-Web assigns are due Tuesday after thanksgiving break.

-Mr. Paek said he will not return our quizzes, but we get to retake one and drop the lowest.

-Mr. Paek also said that if there is anyone who doesn't get the lewis structure, they should go see him ASAP because it's important. The lewis structure is a key concept and you have to completely get it in order to understand upcoming lessons.

Homework:

-Finish up to page 19.

- Make sure you finish the 2 practice sheets we got on Thursday that go along with the chem think.(they might be collected tomorrow.)

In Class:

Well first Mr. Paek introduced to us the concept of VSEPR. He said that he will use this term a lot and he wants us to understand it. here is what each letter stand for:

-V= Valence

-S= Shell

-E= Electron

-P= Pair

-R= Repulsion

-This theory is used to prove that electron want to repel as far away from each other as possible.

-there are 5 types of molecular shapes: linear, bent, trigonal planar, trigonal pyramid, tetrahedral.

*Linear and bent are usually associated with 2 electrons and are are usually 2 dimensioned . (example by Mr. paek: If Mac and Kevin were to have a fight where would they go in the room to be as far away from each other as possible? the answer was in the corners of the room.)

*Trigonal planar, trigonal pyramid, and tetrahedral are associated with 3 electrons and are usually 3 dimensioned.(example by Mr. paek: if Max, Kevin, and Jimmy were to fight over kinga, where would they want to be in the room in order to be as far away from each other as possible? the answer was 2 would be in each corner and one would be in the middle)

- those were examples to help us visualize and help us understand what molecular shapes look like.

-Other key things to remember is that the lone pairs are key because they push everything down and change shape. And for shape you don't need dots unlike lewis structure.

- The picture at the right is page 16: I am going to go over the first one, so you guys get an idea on what we did today.

CS2

Needs: 24; Has:16;Shares:8; Bonds:4 .

I am sure we all know how to draw the lewis structure for this one ( see Mr. Paek if you don't), well the molecular shape is the same as the lewis structure but without the dots. and the name of the shape is linear.

The next scriber will be Andrea.

Thursday 9,16,2010

Today in the beginning of class Mr Paek made a couple of announcements about the upcoming week, here are the dates:

• chem think is due tomorrow-17/9
• web assign is due Monday-20/9
• Quiz on Monday-20/9

Quiz will be on molecules,atoms,compounds, the quiz will also have like 1 density problem and 1 measuring problem.

• lab test Tuesday-21/9
• test - sometime during the week.

Then Mr Paek explained to us the difference between physical and chemical change:

-physical change: do not affect chemical position.

some chemicals present.

same arrangement of atoms.

-chemical change: alter chemical composition

new chemicals formed

bonds broken and formed

rearrangement of atoms

after we did a chemical and physical changes sheet. we had 17 examples, where we had to decide weather the change is physical or chemical.

-some examples:

snow turning into water= physical change

hammering gold into a thin sheet=physical change

phosphorus burning=chemical change

We then did the physical or chemical stations lab: the lab was really easy we had to go through stations.

examples= in station 1 we had to watch melting candle wax, which was physical change. then burn candle wax and wick, which was a chemical change.

in station 4 we had to add water and food coloring, which was physical change. then melt ice in water which also was physical change.