MOLECULAR SHAPES
Name
Linear
Linear
Shape
Degree
180°
180°
Lone
Pairs
Polarity
Bond
Molecule
Polar :
2 different elements
Polar :
2 different elements
Non-Polar:
same elements
Non-Polar:
Non
same elements
Polar :
2 different elements
Polar :
2 different elements
(terminal atoms)
0
0
Non-Polar:
same elements
Non-Polar:
Non
(center and terminal same elements
atoms)
(terminal atoms)
The only difference between the Linear and Bent shapes is the lone pairs on the center atom. The lone
pairs on the center atom will also give you the degree. The more lone pairs it has, the smaller the degree.
degree
1 Lone pair is 120
120° 2 Lone pairs is 109.5°
Now that we get into larger molecules (3-5 atoms), the molecular polarity is determined by two checks.
One is by the lone pairs:
When there is a Lone Pair in the center atom the molecule is automatically Polar,, if there are 0 Lone Pairs
then proceed to the Second check. (Keep in mind that this applies only to 3-5
5 atom molecules).
Second is by the terminal atoms:
If the terminal atoms are different elements it is automatically Polar
Polar, if they are the same element the
molecule is non-polar.
MOLECULAR SHAPES
Bent
120°
1
Polar :
2 different elements
(center and terminal
atoms)
Most of the bonds
will be polar since
they will be
composed of
different elements.
Bent
109.5°
2
Polar :
2 Check Process.
Check 1:
If there is a Lone
Pair in the center
atom, the molecule
is automatically
Polar.
If there are 0 Lone
Pairs then proceed
to the Second check.
Check 2:
If the terminal
atoms are different
elements.
Trigonal
Planar
120°
0
Trigonal
Pyramidal
109.5°
1
Tetrahedral
109.5°
0
Non-Polar:
This is only possible
when the center
atom has 0 Lone
Pairs and the
terminal atoms are
the same kind of
element.
MOLECULAR SHAPES
The best ways to remember all this information is by breaking everything down into individual parts.
1st remember the names: The names can be determined by the shape and angle of the molecule.
Linear = is just a line of atoms with a 180° angle. Notice that it's 2 or 3 atoms total.
Bent = Linear but bent due to the Lone Pairs that it contains, the more Lone Pairs the greater the bent
and the smaller the degree. It is 3 atoms total.
Trigonal Planar = the way I remember this name is by the "Tri" which makes me think of 3 terminal atoms
and the word planar makes me think of something plane which means nothing extra (0 Lone Pair).
Trigonal Pyramidal = also focus on the “Tri” (3 terminal atoms), but mainly that it contains 1 Lone Pair.
Tetrahedral = is a fully bonded molecule, and I use the word "Tetra" to remind me that there are 4
terminal atoms.
2nd: The degrees, notice that when you have the center atom fully loaded on all 4 directions (either by
bonds or Lone Pairs) the degree is smaller. So the degrees are totally dependent on the bonds and Lone
Pairs.
Finally: The Polarity. If you follow the Notes I wrote, you will not have a problem.
Good Luck!!