Chemistry Reference
In-Depth Information
Lesson 4-5 Review
Base your answers to questions 1-6 on the following images:
H
HO
H
N
H
H
HH
B
H
A.
C.
E.
Cl
O CO
S
Cl C
Cl
Cl
B.
D.
F.
1.
Which image shows a compound that has a tetrahedral shape?
2.
What would cause the compound shown in image C to form a
different shape than the compound shown in image E?
3.
What shape does the molecule from image A show?
4.
Which image shows a linear molecule?
5.
What shape molecule would the atom in image F form if it acts as the
central atom, bonded to two other atoms?
6.
What is the shape of the molecule formed by the compound shown in
figure E?
Lesson 4-6: Polarity of Molecules
When we talk about the polarity of molecules, we are talking about
whether the molecule has positive and negative poles, like a bar magnet. A
polar molecule—that is, one with a positive and negative side—must con-
tain one or more polar covalent bonds and it must have asymmetrical mo-
lecular geometry. A non-polar molecule either has symmetrical molecular
geometry, or it only has non-polar covalent bonds, or both. This will be
made clear as we go over some examples, but in the meantime, try to com-
mit the little flowchart on page 139
to memory.
Now, we need to explain the idea of symmetry. You may have encoun-
tered the term symmetry in biology class. Humans are said to have bilateral
symmetry, because if you draw a line straight down from the center of your
head, your two “halves” look the same. If you can draw a line across a
molecule and divide it into unequal looking halves, then it is asymmetrical.
