VSEPR THEORY
UNIT 6.5
VSEPR THEORY
Valence Shell Electron Pair Repulsion (VSPER) theory is used
to predict the geometric shape of the molecules based on
the electron repulsive force…
In other words:
shared e- and unshared e-- get as far away from one another as possible.
This helps us predict what a molecule REALLY looks like (they’re 3D not 2D)
MOLECULAR SHAPES (5)
Linear
Bent
Trigonal Planar
Tetrahedral
Trigonal Pyramidal
LINEAR
Linear shape - all 2 atom molecules (AB) also 3 atoms, no
unshared e-- on the central atom (AB2)
Ex. CO2
TETRAHEDRAL
Tetrahedral Shape - 4 attached atoms to central atom. (AB4)
No unshared e-
Ex. CH4
TRIGONAL PYRAMIDAL
Trigonal Pyramidal Shape- 3 atoms attached to central, 1 pair
of unshared e-- (AB3E1)
Ex. NH3
BENT
Bent Shape - 2 atoms surrounding the central and 2
unshared pairs of e--. (AB2E2)
Ex. H2O
TRIGONAL PLANAR
Trigonal Planar Shape - 3 atoms surrounding a central atom
(AB3). No unshared e-
Ex. BF3
IDENTIFY THE FOLLOWING SHAPES
Determine the shape of CCl4 by drawing its Lewis Dot Structure.