1. Forming single, double, and triple bonds
Covalent Bonds
Forming single, double, and triple bonds

2. Covalent Bonding
Remember, when atoms bond covalently, there is a sharing of electrons between the two atoms.
However, not all of the electrons are involved in the bond, so there are two different types of electron pairs.
Bonding Pair: Shared pairs (shown by lines)
Lone Pairs: Unshared pairs (shown by pairs of dots)

3. There are also a few types of covalent bonds and the type of covalent bond depends on how many pairs of electrons are shared.

4. Single Covalent Bonds 1 Examples: F2, NH3, CH4
The sharing of ______ pair of electrons
Examples: F2, NH3, CH4 C H F H N

5. Double Covalent Bonds 2 Examples: O2 and H2CCH2
The sharing of ______ pair of electrons
Examples: O2 and H2CCH2 O C H

6. Triple Covalent Bonds 3 Examples: N2 and HCN
The sharing of ______ pair of electrons
Examples: N2 and HCN N N C H

7. Strength of Bonds
bond
Distance separating nuclei - _________ ___________
Depends on the size of the atoms - _________ ___________
Pairs shared – more electrons shared, _________ ___________
(_____________ has smallest bond length)
Smaller bond length - _________ ___________
length
atomic
radii
closer
together
Triple bond
stronger
bond

8. Strength of Bonds
Bond dissociation energy – energy to _________ ___________
Energy must be _________ to break bonds
Bond dissociation energy is always _________
Direct relationship between bond energy and bond length - _________ bond length, _________ bond, _________ bond energy
break
bonds
added
added
smaller
stronger
more

9. So, how do scientists decide how many electrons are shared
So, how do scientists decide how many electrons are shared? One way is by drawing Structural Formulas a.k.a. Lewis Formulas

10. Add up total number of ________ electrons.
Rules:
valence
Add up total number of ________ electrons.
Place atoms on center or sides....how?
Connect each atom with a _________ bond, then subtract from total number (2 per line).
If any electrons are left, place pairs of electrons on the __________ atom(s) until they are “___________”.
Remember, Hydrogen can only make ______________
Single element in center first
Least electronegative in center if there is a choice
Hydrogen is never in the middle
single
outside
happy
one single bond

11. 5. If any electrons are left, place them on the center atom.
6. When you are at 0 pairs, make sure everyone is “happy”:
Happy Hydrogen :____________
Happy everyone else:__________
7. Remember a line represents ___ electrons.
8. If everyone is happy then.....Finished. If everyone is not happy then you must share extra pairs and form double or even triple bonds.
2 electrons
8 electrons 2

12. Let’s try some examples
H2O
CF4

13. NCl2Br
CO2

14. Polyatomic Ions
Take charge into consideration. (Add negative to total, subtract positive from total of electrons.)
Put brackets around structure with charge on outside right corner

15. Let’s look at CO32- and NH4+1