Non-Polar Vs Polar Molecules

The main idea today in class was non polar vs polar molecules.....

Non Polar Molecules

Non polar molecules have symmetry (the charge is evenly spread throughout the molecule) They dont have a positive and negative side. Non Polar molecule NEVER have NON BONDING PAIRS. Non bonding pairs would give the molecule a higher concentration of negative charge on one side, making it polar. It is possible for non polar molecules to have polar bonds, so be careful when determining wether or not it is non polar, its all about the symmetry.

These 2 molecules (CCl3 & BF3) are non polar because the charge is evenly distributed. SYMMETRY!

Polar Molecules

Polar molecules do not have symmetry, they have negative and positive ends. This could be causes by non bonding pairs, which will cause a molecule to have a high concentration of negative charge on one end. It could also be caused by a molecule with more than 2 different atoms around the central atom, one of them having a higher electronegativity will cause more negative charge concentration on one side making it POLAR. A great example of a polar molecule is H2O, or water. Since O has a higher electronegativity then H, all the negative charge concentrates around the O. This causes the O side of this molecule to be negative, and the H side, to be positive. Here are some pictures of Polar Molecules...

Liebs did a demo to show the polarity of water. He had a balloon and he rubbed it against his head. This caused the balloon to take a negative charge. There was also a stream of water dripping from a glass cylinder. When liebs put the balloon close to the water, the water bends towards the balloon. What actually happens is the positive side of the H2O molecule (the H side) is attracted to the balloon. Hopefully now you know more about polar and non polar molecules....

The HW is to make sure you are keeping up with the webassigns