Covalent Bonding
Unit 2
Chemistry 11
Mrs. Purba
Homework Solutions
Homework Solutions
Homework Solutions
Homework Solutions
Homework Solutions
Homework Solutions
A covalent bond is a chemical bond in which two or more electrons are
shared by two atoms.
Why should two atoms share electrons?
F
+
7e-
F
F F
7e-
8e- 8e-
Lewis structure of F2
single covalent bond
lone pairs
F
F
single covalent bond
lone pairs
F F
lone pairs
lone pairs
Lewis structure of water
H
+
O +
H
single covalent bonds
H O H
or
H
O
H
2e-8e-2eDouble bond – two atoms share two pairs of electrons
O C O
or
O
O
C
double bonds
- 8e8e- 8ebonds
double
Triple bond – two atoms share three pairs of electrons
N N
triple
bond
8e-8e
or
N
N
triple bond
9.4
Lengths of Covalent Bonds
Bond Lengths
Triple bond < Double Bond < Single Bond
Polar covalent bond or polar bond is a covalent bond with
greater electron density around one of the two atoms
electron poor
region
H
electron rich
region
F
e- poor
H
d+
e- rich
F
d-
9.5
Electronegativity is the ability of an atom to attract toward itself
the electrons in a chemical bond.
Electronegativity – Linus Pauling Scale, F is highest
The Electronegativities of Common Elements
Classify the following bonds as ionic, polar covalent,
or non-polar covalent…the bond in CsCl; the bond in H2S; and
the NN bond in H2NNH2.
Cs – 0.7
Cl – 3.0
H – 2.1
S – 2.5
3.0 – 0.7 = 2.3
2.5 – 2.1 = 0.4
N – 3.0
N – 3.0
3.0 – 3.0 = 0
Ionic
Polar Covalent
Non-polar
Classification of bonds by difference in electronegativity
Difference
Bond Type
0
 1.7
0 < and < 1.7
Non-polar Covalent
Ionic
Polar Covalent
Increasing difference in electronegativity
Non-Polar Covalent
share e-
Polar Covalent
Ionic
partial transfer of e-
transfer e9.5