Worksheet: Chapter 14
Name ________________________
1. A water molecule has an angular shape. Sketch a diagram of a water molecule and label
the positive and negative ends of the molecule.
2. State a difference between polar covalent bonds and nonpolar covalent bonds.
Polar covalent bonds are when electrons are shared unequally between different
nonmetal atoms. Nonpolar covalent bonds are when electrons are shared equally
between nonmetal atoms which are the same.
3. What is the difference between a polar molecule and a nonpolar molecule?
A polar molecule is a molecule that is not symmetric. That is it has one end which
is different than the other. This causes one end of the molecule to be positive and one end
of the molecule to be negative. Nonpolar covalent molecules are symmetric and therefore
do not have different ends to them.
4. Carbon tetrachloride (CCl4) has polar bonds however it is not a polar molecule. How is
this possible?
The polar bonds are symmetrically arranged so that every end of the molecule is
the same.
5. Use the shapes of the molecules to explain why H2O is a dipole but CO2 is not. (A dipole
is a polar molecule.)
Water is a bent molecule which has oxygen on one end and hydrogen on the other.
CO2 is linear and has an oxygen on either end.
6. What are Van der Waals forces?
Weak attractive forces holding adjacent molecules together.
7. Octane (C8H18) is a liquid at room temperature and propane (C3H8) is a gas. Explain this
observation.
Octane is a larger molecule than propane and therefore has stronger Van der
Waals forces.
8. Two molecules are about the same size however one is a liquid at room temperature
whereas the other is a gas. Suggest a reason for this observation.
One molecule is polar and therefore has stronger Van der Waals forces
which enable it to attract better and be a liquid. The gaseous molecule must be
nonpolar and therefore does not have as much Van der Waals forces.