1. Warm-Up What is a covalent bond?
What types of elements form covalent bonds?

2. Nonmetals Join Together
Covalent Bonding
Nonmetals Join Together

3. Covalent Bonding
Covalent Bond – a bond in which two nonmetals share one or more of their valence electrons
Polar – unequal sharing of electrons
Nonpolar – equal sharing of electrons
Smallest unit is called a molecule
Common Examples: (Know these!)
Diatomic elements
Water (H2O)
Ammonia (NH3)
Methane (CH4)

4. Bond Polarity
Unequal sharing of electrons is due to a difference in electronegativity (ΔEN) of the two atoms
Ionic Bond: ΔEN ≥ 1.7
Ex: NaCl
Polar Covalent Bond: 0.4 < ΔEN < 1.7
Ex: H2O
Nonpolar Covalent Bond: ΔEN ≤ 0.4
Ex: CH4

5. Calculating ΔEN
∆EN= EN Element 1 − EN Element 2

6. Covalent Bond Lengths
Valence electron orbitals of each element overlap as electrons are shared
More shared electrons creates a shorter and stronger bond

7. Covalent Properties Low melting and boiling points
Many are liquids and gases at room temperature
Soluble in water IF they are polar (like dissolves like)
Do not conduct electricity

8. Lewis Dot Structures
Show the symbols, valence electrons, and bonds in a covalent compound
Dictated by The Octet Rule (all atoms want to have 8 valence electrons)
Exception: Hydrogen only needs 2
Exception: Boron can only get 6

9. Steps to Draw Draw out each atom with its valence electrons
Move electrons to share until all atoms have full outer shells
Redraw

10. Drawing Hints Put the single atom in the middle of the dot structure
Hydrogen is NEVER in the middle of the dot structure
A dash connecting two atoms represents a pair of shared electrons
Sometimes, more than one pair of electrons is shared
Two pairs = double bond
Three pairs = triple bond
Don’t forget to re-draw non-bonding electrons!

11. Example 1
CH4

12. Example 2
PCl3

13. Example 3
H2S

14. Example 4
HCl

15. Example 5
CO2

16. Example 6
BH3