Problem Set: Polar, Nonpolar,
and Ionic Bonds
KEY
1. Distinguish between polar and
nonpolar bonds.
• Polar = e- are shared unequally
• Nonpolar = e- are shared equally
2. Why is an HCl molecule polar
while a Cl2 molecule is nonpolar?
• H & Cl have different electronegativities;
therefore they form a polar bond.
• Cl & Cl have same electronegativity;
therefore they form a nonpolar bond.
3. Why do we show only partial
charges, and not full charges, on
atoms of a polar molecule?
• Electrons are more attracted to one atom
in a polar molecule; however they do not
completely transfer from one atom to
another.
4a. Which of the following pairs of elements
are most likely to form ionic bonds? (show
why using electronegativity values)
• Te and H
2.1 and 2.2
0.1
• C and F
2.5 and 4.0
1.5
• Ba and F
0.9 and 4.0
3.1
• N and F
3.0 and 4.0
1.0
• K and O
0.8 and 3.5
2.7
4b. Of the remaining 3 pairs of elements,
which one forms the least polar, and which
the most polar, covalent bond? (Show why
using electronegativity values).
• Least polar = Te and H (Δ=0.1)
• Most polar - C and F (Δ=1.5)
5) Classify the bonding between the following pairs of
atoms as ionic, covalent very polar, covalent moderately
polar, or covalent nonpolar (show with electronegativity
values and differences WHY you classify each one):
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Si & O = 1.6 = covalent very polar
N & O = 0.5 = covalent slightly polar
Li & O = 2.5 = ionic
Br & I = 0.3 = nonpolar
O & O = 0.0 = nonpolar
Sr & F = 3.1 = ionic
As & As = 0.0 = nonpolar
N & F = 1.0 = covalent slightly polar
Ca & H = 1.2 = covalent very polar
H & O = 1.3 = covalent very polar
6a) Write Lewis dot formulas for atoms of
strontium, chlorine, and silicon.
6b) Use the appropriate pairs of these atoms
to show formation of: an ionic compound
and a covalent molecule.
6c) Indicate the polarity of the bond in the
covalent molecule (with polarity arrows, or
with partial positive and negative charges).
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
a) H2O
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
b) O2
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
c) NCl3
NONPOLAR
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
d) CO32-
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
e) HCO3-
7) Draw Lewis structures for the following covalent
compounds, and label the positive and negative
ends or regions of the molecule (if applicable):
f) ClO3-