Sharing is Caring

Today, Mr. Lieberman had a pack of sour patch kids. He shared them with Zoe by giving her 1 of them and eating the rest. With a second pack of candy, he gave half to Zoe and the rest he ate. With a third, he gave the whole pack to Katie, taking none for herself. We learned that Mr. Lieberman was sharing his candy as molecules share electrons.
First, we learned about polar and non-polar. These are only between 2 nonmetals.
Polar covalent bonds are where electrons are not shared equally between molecules, and the electronegativity difference is between 0.4 and 1.7.
Non-polar covalent bonds are where electrons are shared equally between molecules, and the electronegativity different is between 0 and 0.4.
An example of a non-polar covalent bond is C-C. It is said to be like "tug of war with your twin". No one would win and the forces trying to win, or gain the electrons are equal, so the electrons would be shared equally. The electronegativity for the two atoms are the same, so they are equally pulling for the electrons. This is the scenario where Mr. Lieberman gave half his candy to Zoe and kept half for himself.
An example for a polar covalent bond would be C-F. The electronegativity for fluorine is strong than that of carbon, and therefore, there is an unequal share of electrons, because flourine would be winning the game of tug of war with carbon. Fluorine becomes more negative because the electrons are closer to fluorine than carbon, even though they are still shared with carbon, so that would mean fluorine is partially negative. Carbon has less of a pulling force on the electrons so it is partially positive. The opposite ends (+ and -) create a dipole. This is the scenario where Mr. Lieberman gave one piece of candy to Zoe and ate the rest.
Ionic bonds are where one molecule gets all the electrons, having a complete transfer, even though this is considered sharing. The electronegativity of one nonmetal atom is so much greater than the other metal atom that it pulls the electrons away. This is the scenario where Mr. Lieberman gave all his candy away to Katie.
We also had a pop quiz at the end of class.
Have a great rest of the weekend everyone!
~Kaitlyn Y.
The next scribe will be Elim.

Bubbles

Today, we did the Molar Volume Lab. Here's what happened.
First, we cut a piece of magnesium in half and measured its length because we would not be able to find the mass on a scale. Magnesium is .01085 g/cm. Our piece of magnesium was 2.5 cm. Then, we tied a piece of copper wire around the magnesium ribbon so that the magnesium would not float around in the eudiometer. (http://www.flickr.com/photos/hc1011/5258241891/) The eudiometer is a gas collection tube, measuring gas by water displacement. We poured 10 ml of HCl and 100 ml of water into the eudiometer. The temperature of the tap water was 21.3°C. Room temperature was 22.2°C and the barometric pressure was 30.11 inHg (we have to convert it to mm). We put the cork attached to the copper wire and magnesium at the open end. We then flipped the eudiometer over, safely and carefully, and put the cork end into a beaker with water and clamped the eudiometer so it would stay up. We watched as the magnesium reacted with the HCl and created bubbles of hydrogen. (http://www.flickr.com/photos/hc1011/5258850050/) Slowly, the water was going into beaker and leaving space at the top of the eudiometer. While we waited for the reaction to finish, we recorded the room temperature and the barometric pressure at room temperature. Once the reaction stopped bubbling, we took the eudiometer to the fume hood and measured the volume of the gas. The volume of the gas was 27.4 ml of hydrogen. (http://www.flickr.com/photos/hc1011/5258850358/)
This lab is due Wednesday. Our test for this unit is Friday. Sorry about the pictures, they won't show up. So I included the links to them.
This has been Kaitlyn. (with a Y!) Thank you, thank you very much. :)
The next scribe will be Matt P!

Wholly GuacaMOLE!!!

Today, we began by getting back our tests from last week. After going through some of our mistakes and questions, Mr. Lieberman suggested that if you still have troubles with naming compounds, you should practice some more problems. Then, we moved on to notes about the mole.
The mole is a counting unit that means 602 billion trillion (similar to a dozen, which is 12) or 602,000,000,000,000,000,000,000, or in scientific notation 6.02x10^23. It is also known as Avogadro's number in honor of Avogadro. A mole is really large in terms of things that we can see, such as soft drink cans, as Avogadro's number of these can cover the surface of the earth to a depth of 200 miles.
The mole is used in the same way a dozen is used:

• 1 dozen cookies=12 cookies
• 1 mole of cookies=6.02x10^23
• 1 dozen cars=12 cars
• 1 mole of cars=6.02x10^23

*The number is always the same, but the mass is different* (Mole is abbreviated mol.)

Moles of particles:

• 1 mole of carbon = 6.02x10^23 C atoms
• 1 mole of H2O = 6.02x10^23 H2O molecules (2 moles of hydrogen and one mole of oxygen)
• 1 mole of NaCl = 6.02x10^23 NaCl "molecules" (6.02x10^23 Na^+ ions and 6.02x10^23 Cl^- ions)

Molar Mass: the mass of 1 mole (in grams) is equal to the numberical value of the average atomic mass (from the periodic table)

• 1 mole of C atoms = 12.0 g
• 1 mole of Mg atoms = 24.3 g
• 1 mole of Cu atoms = 63.5 g

To find the molar mass of molecules and compounds, you add the molar masses together:

1 mole of CaCl2 = (1 mole of Ca x 40.1 g/mol) + (2 moles of Cl x 35.5 g/mol) = 111.1 g/mol CaCl2

Here are some notes for calculations with moles:

• For grams to moles, divide by molar mass
• For moles to grams, multiply by molar mass
• For particles to moles, divide by Avagadro's number
• For moles to particles, multiply by Avagadro's number

The artificial sweetener aspartame has the formula C14H18N2O5. To find out how many moles of aspartame are in 225g of aspartame: 225g of C14H18N2O5 x (1 mol/294 g/mol) = .765 moles of aspartame. (the 294 is from C14 (14x2) + H18 (18x1) +N2 (2x14) + O5 (5x16) = 294 g/mol)

Sorry about the bad formatting. I still couldn't insert the exponents and other such things. For more information about the mole, visit http://www.visionlearning.com/library/module_viewer.php?mid=53 and for more information about Avogadro, visit http://chemistry.about.com/od/famouschemists/a/avogadro.htm.

Don't forget about the worksheet from last week as well as the one from today. Also, there is a quiz on Wednesday!

~Kaitlyn Y.

The next scribe is Alex K.