Covalent Compounds
Diatomic Molecules: H2, N2, O2, F2, Cl2, Br2, I2
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Prefixes for Binary Covalent Compounds:
Prefix
mono di
Number
Exception for mono:
tri
tetra
penta hexa
Example: Name these compounds—(a) N2O
(b) PCl3
hepta octa
(c) AlCl3
nona
deca
(d) SF6
Practice:
1. Name these compounds:
(a) CBr4
(b) Cl2O7
(c) N2O5
(d) BCl3
(e) CrCl3
2. Write the formulas for these compounds:
(a) carbon disulfide
(c) carbon tetrachloride
(b) dinitrogen tetrahydride
(d) diphosphorus trioxide
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Drawing Structures:
Practice: Draw electron dot structures for the following compounds—
(1) NH3
(2) BeH2
(3) BF3
(4) CCl4
Practice: Draw structural formulas for the compounds in the previous practice problem.
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Polarity:
Electronegativities
H
2.20
Li
0.98
Be
1.57
B
2.04
C
2.55
N
3.04
O
3.44
F
3.98
Na
0.93
Mg
1.31
Al
1.61
Si
1.90
P
2.19
S
2.58
Cl
3.16
K
0.82
Ca
1.00
Ga
1.81
Ge
2.01
As
2.18
Se
2.55
Br
2.96
Rb
0.82
Sr
0.95
In
1.78
Sn
1.96
Sb
2.05
Te
2.10
I
2.66
Cs
Ba
Tl
Pb
Bi
Po
At
0.79
0.89
1.80
1.80
1.90
2.00
2.20
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Electronegativity Differences: (When computing, do not round up.)
*NONPOLAR (less than 0.4)
*POLAR (0.4 to 2.0)
*IONIC (more than 2.0)
Example: What type of bond (polar, nonpolar, ionic) will form:
1. between atoms of: (a) N & H
(b) Ca & O
2. in the compounds: (a) H2O
(b) F2
Practice 1:
1. Identify the bond type (polar, nonpolar, ionic):
a. Between atoms of: (1) H & Br
(2) K & Cl
b. In compounds of: (1) CO2
(2) Li2O
2. Which covalent bond is the most polar?
a. H – Cl
b. H – Br
c. H – S
d. H – C
(3) Br & Br
e. F – F
Practice 2: What kind of van der Waals force would exist in each of the following
situations? How do you know?
1. Cl2 & SO2
2. CH4 & N2
3. ICl & N2O5