1. Electronegativity and Forces

2. 3 types of bonds
There are three types of chemical bonds that can form between atoms:
Ionic bonds
Polar Covalent bonds (partly share electrons)
Non-polar Covalent bonds (equally share electrons)

3. Electronegativity
How do we measure how strong the atoms pull electrons = which of the 3 bond types is it?
Electronegativity = measure of how strongly a specific element attracts electrons.
Table on page 265 in textbook.

4. Electronegativity
The bigger the electronegativity DIFFERENCE the more polar the bond. Process: Subtracting the electronegativity of one element versus one of another element.

5. Electronegativity
Ranges: Less than 0.4 = nonpolar covalent Between 0.4 and 1.7 = polar covalent (partial ionic character) Greater than 1.7 = ionic

6. Showing a polar bond Isn’t a whole charge just a partial charge
d+ means a partially positive
d- means a partially negative
The Cl pulls harder on the electrons
The electrons spend more time near the Cl

7. Intermolecular Forces
All atoms and molecules attract to each other, but vary by the amount of attraction
London forces attract non-polar molecules or atoms together
(non-polar means there are no partial charges within the molecule, i.e. covalent)
Animation:

8. Intermolecular Forces
Dipole forces attract polar molecules together:
the partial negative side attracts to the positive side of the next molecule

9. Intermolecular Forces
Hydrogen bonds are especially strong dipole forces between hydrogen atoms and either oxygen, fluorine, or nitrogen.
This is because hydrogen is so small and can get so close to the other atoms.
Hydrogen bonds are not actual chemical bonds, just intermolecular forces

10. Diatomics
Diatomic = Molecules that are composed of two of the same element only. Examples: H2, N2, O2, F2, Cl2, Br2, I2, At2