1. Hydrogen and Chlorine:
Covalent Bonding:
Hydrogen and Chlorine:
Covalent Bonding: H Cl
or H-Cl H + Cl
Sharing electrons
2) Hydrogen & hydrogen.
(Single covalent bond)
3) Fluorine & fluorine.
4) Nitrogen & hydrogen.
5) Carbon & hydrogen.

2. Covalent Bonding: The Octet Rule in Covalent Bonding
In covalent bonds, electron sharing
usually occurs so that atoms attain
the electron configurations of noble
gases.
The pair of shared electrons forming the
covalent bond is also often represented
as a dash, as in H—H for hydrogen
(structural formula )

3. Covalent Bonding: Formation of chemical bonds (Lewis dot structure):
1)Oxygen and oxygen: O O
or O=O O + O
Two pairs of
electrons shared
(Double covalent bond)
A double covalent bond is a bond that
involves two shared pairs of electrons.

4. Three pairs of electrons shared
2) Nitrogen & nitrogen: N + N
or N N N N
Three pairs of electrons shared
(Triple covalent bond)
Similarly, a bond formed by sharing three
pairs of electrons is a triple covalent bond.

5. Using electron-dots structure represent the following molecules:
CO2
2) C2H4
3) C2H2

6. Bond Polarity:
How do electronegativity values determine the charge distribution in a polar bond?
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7. Bond Polarity
The nuclei of atoms pull on the shared electrons, much as the knot in the rope is pulled toward opposing sides in a tug-of-war.
The bonding pairs of electrons in covalent bonds are pulled between the nuclei of the atoms sharing the electrons.

8. Bond Polarity
A polar covalent bond, known also as a polar bond, is a covalent bond between atoms in which the electrons are shared unequally.
The more electronegative atom attracts more strongly and gains a slightly negative charge.
The less electronegative atom has a slightly positive charge.
δ δ–
H—Cl
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9. Bond Polarity H-H Br-Br O=O
When the atoms in the bond pull equally (as occurs when identical atoms are bonded- same electronegativity), the bonding electrons are shared equally, and each bond formed is a nonpolar covalent bond.
H-H
Br-Br
O=O
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10. Bond Polarity
The electronegativity difference between two atoms tells you what kind of bond is likely to form.
Electronegativity Differences and Bond Types
Electronegativity difference range
Most probable type of bond
Example
0.0 – 0.49
Nonpolar covalent
H—H (0.0)
0.5 – 0.99
Moderately polar covalent
δ+ δ–
H—Cl (0.9)
1.0 – 1.99
Very polar covalent
H—F (1.9)
≥ 2.0
> 1.5
Ionic
Ionic (if a metal is present)
Na+Cl– (2.1)
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11. Electronegativity Chart
Sample Problem
Identifying Bond Type
Which type of bond (nonpolar covalent, moderately polar covalent, very polar covalent, or ionic) will form between each of the following pairs of atoms?
a. N and H
b. F and F
c. Ca and Cl
d. Al and Cl
Electronegativity Chart
Page 181

12. Calculate the electronegativity difference between the two atoms & determine the bond type.
a. 3.0(N) - 2.1(H) =
0.9
Moderately polar covalent.
Nonpolar covalent.
b. 4.0(F) - 4.0(F) =
0.0
c. 3.0(Cl) - 1.0(Ca) =
2.0
Ionic.
d. 3.0(Cl) - 1.5(Al) =
1.5
Very polar covalent.
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13. Electronegativity:

14. Examples: Cl2(g), Br2(l), CCl4(l).
Properties of Molecular Compounds:
1) Weak attraction forces between molecules.
2) Low melting and boiling points.
3) Gases, liquids or solids at room temperature.
4) The solids are very soft.
5) Poor conductors of electricity.
6) Polar covalent: Show solubility in water.
Ex. HCl(g), NH3(g)
No polar covalent: Show solubility in non polar
solvents (CCl4, oil, gasoline, acetone, etc.)
Examples: Cl2(g), Br2(l), CCl4(l).

15. Covalent Network Solids:
A network solid or covalent network solid is a chemical compound in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material
Examples:
Quartz or Silica
(SiO2 silicon dioxide),
diamond & graphite
(made by carbon).
diamond graphite

16. Covalent Network Solids:
Properties:
1) Brittle & extremely hard solids.
2) Very high melting points.
3) Non conductors (heat or electricity),
except graphite (good conductor)