1. Non-polar and Polar Covalent Bonds
Section 8.4 pages , 229

2. But now we’re going to look at HOW an atoms shares electrons
Atoms with unfilled valence shells are considered unstable. Atoms will bond with other atoms in an effort to fill their valence shells and become stable.
Let’s Review!
Atoms will form ionic bonds
Atoms will form covalent bonds
Between two non-metals.
By sharing electrons
By transfering electrons
Between a metal and a nonmetal
But now we’re going to look at HOW an atoms shares electrons

3. Polar vs Non Polar Bonds
When forming covalent bonds, atoms will SHARE electrons in different ways.
There are two types of covalent bonds:
Nonpolar covalent bonds- bonds that share electrons equally, similar to an evenly match game of tug if war
ex. Hydrogen bonded to hydrogen H-H or lipids (fats)
2. Polar covalent bonds- bonds that share electrons unequally
similar to an uneven game of tug-of-war. Ex. HCl or H2O
In a polar bond, the atoms with more protons attracts the electrons more strongly, gaining a more negative charge.
The atoms with less protons ends up with the electrons
less of the time resulting in a more positive charge.

4. Characteristics of Non-Polar Bonds
Non-polar molecules share electrons
evenly in their covalent bonds.
Non-polar molecules are neutral overall because the electrons are shared equally.
Non-polar molecules will have different properties than polar molecules.
Non-polar molecules will NOT dissolve in polar substances.
Ex. Fats/lipids are all non polar.
Non polar can dissolve other non polar molecules
(ex. Grease and soap, both nonpolar)

5. Water (H2O) is an example of a polar molecule.
Polar Bonds:
Water (H2O) is an example of a polar molecule.
Q. Is hydrogen or oxygen more electronegative?
A.Oxygen has more protons and therefore will pull the electrons closer to itself.
As a result:
oxygen becomes slightly negative (-).
hydrogen becomes slightly positive (+).
The positive regions in one water molecule attract to the negative regions in another.
This allows water molecules to “stick”
to one another through bonds called
hydrogen bonds.

6. Hydrogen Bonds- bonds that hold water molecules together
And now for a romantic animation of water molecules being attracted to other water molecules through Hydrogen bonds

7. Using the Water molecule below: 1. Label the hydrogen atoms 2
Using the Water molecule below: 1. Label the hydrogen atoms 2. Label the oxygen atoms 3. Include the charge for both the oxygen and hydrogen

8. Water is POLAR! Because of its polarity water has some very unique properties and can do some neat stuff!

9. Two properties of water result from Hydrogen Bonding
Cohesion- attraction of molecules of the same substance (ex. water attracted to water)
> Surface tension- cohesion of water molecules at the surface of a body of water ex. bug “walking on water”

10. Two properties of water result from Hydrogen Bonding
Adhesion – attraction between molecules of different substances
(ex. Water molecules attracted to a glass)
> Capillary Action- the adhesion of water molecules & another substance moving up against gravity

11. Contrasting Nonpolar vs Polar Molecules
Nonpolar Molecules
Polar Molecules
Share electrons evenly
Neutral (even) charge surrounding the molecule
Nonpolar can dissolve nonpolar molecules
Examples: lipids/fats
Share electrons unevenly
Uneven charge surrounding the molecule
Polar can dissolve other polar and ionic molecules (not nonpolar)
Examples: Water