124
ci
ci
CI'
V CI
ClTnangle coplanar
'CI
FIGURE 9-4
Triangular-coplanar molecule.
For CC1 4 , with P = 4, the molecular structure is tetrahedral with C at the
center, because BP also is 4 (Figure 9-5).
ci
Tetrahedral
FIGURE 9-5
Tetrahedral molecule.
The ammonia molecule is another in which/" = 4, but the molecule is called
pyramidal, not tetrahedral, because there are only three bond pairs (Figure 9-6).
At the apex of the pyramid is the N atom, and the lone pair of electrons
Pyramidal
FIGURE 9-6
Pyramidal molecule.