1. Polar & non-polar covalent bonds
animations

2. Expectation 5
Electronegativity: decides who “wins” the fight over bonding atoms.
The difference in electronegativity between atoms decides the type of bond.

3. Electronegativity & bond type (expectation 5)
The attraction to a bonding electron
The difference in electronegativity decides the type of bond.
Ionic bond: Difference is > 2.0 (between metals & non-metals) & results in ions due to electron transfer.
Polar covalent: Difference is > 0.4 but < 2.0 & results in unequal sharing
Non-polar covalent: difference is < 0.4 & allows equal sharing

4. Covalent bonds (Expectation 7)
When electronegativity values are high, each atom fights to keep the electrons so they must share electrons to satisfy the octet rule.
A covalent bond is when atoms share electrons & stay together because both have ownership over the electrons.
There are 2 types of covalent bonds.

5. Non-polar bonding (expectation 7)
Small or no difference in electronegativity results in atoms sharing electrons equally
No + or – exist.
They do not have to both be
the same atom to be non-polar.

6. Polar covalent bonds (expectation 7)
The atom with greater electronegativity pulls the shared electrons closer to it, resulting in unequal sharing.
Eg. Cl-F
The F atom is slightly negative ( ) because the electrons are closer to F.
The Cl atom is slightly positive ( ) because the electrons are farther from Cl.
Unequal sharing of electrons produces partial charges (poles: opposite charged ends).

7. Polarity (Expectation 10)
Polarity exists if a molecule has charged poles (opposite ends) due to electronegativity differences
These molecules are attracted to other molecules with a charge.
The more similar the polarities are the easier the two substances mix.

8. Polarity & shape
A molecule can have polar bonds & be a polar molecule.
Eg. Which atom is sort of negative & sort of positive?
 S-O H-Cl C-O
 A molecule can have a polar bond & NOT be a polar molecule.
 Eg. CO2 looks like O-C-O
 Both oxygens pull equally & cancel each other out so there is no polar end.
 The shape of a molecule can affect whether a molecule is polar. Polar bonds can cancel each other out.

9. Memorize Salt (NaCl) is ionic. Water is polar. Oil is non-polar.
Ionic compounds (salt) can dissolve in polar substances (water).

10. Ionics dissolve in water
The polarity of water explains the fact that ionic compounds dissolve in water. The charges of the ions in the ionic bond are attracted to the polar ends of water (the “sort of” negative & “sort of” positive charges).

12. Ionic
Large electronegativity difference results in one atom taking the electron.
MgO Oxygen’s has a high electronegativity & Mg is low.
Bonding electron distribution
Mg is + & O is – so they stick together