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286
Chapter 9: Molecular Structures
(e) PF 5 (40 e – ) The type is AX 5E 0, so it is triangular bipyramidal.
. . . F.
..
. .. F
..
. .
F
P
.
. F.
.
..
.. F .
F
F
F
P F
14. Define the problem: Write Lewis Structures for a list of formulas and identify their shape.
Develop a plan: Follow the systematic plan for Lewis structures given in the answers to Question 8.15, then
determine the number of bonded atoms and lone pairs on the central atom, determine the designated type
(AX nE m) and use Table 9.1.
Execute the plan:
(a) NH 2Cl (14 e – ) The type is AX 3E 1, so the electron-pair geometry is tetrahedral and the molecular
H
..
N H
.
. .
geometry is triangular pyramidal.
Cl Cl
N
F
H H
(b) OCl 2 (20 e – ) The type is AX 2E 2, so the electron-pair geometry is tetrahedral and the
..
. Cl.
. ..
. . .
. .
O Cl
molecular geometry is angular (109.5°).
(c) SCN – (16 e – ) The type is AX 2E 0, so the electron-pair geometry and the molecular
. . .
S C N.
. .
geometry are both linear.
(d) HOF (14 e – ) The type is AX 2E 2, so the electron-pair geometry is tetrahedral and the
H
.
. .
..
.. .
O F
Cl
O
Cl
molecular geometry is angular (109.5°).
15. Adapt the method given in the answers to Question 13.
(b) PH 4 + (8 e – ) The type is AX 4E 0, so it is tetrahedral.
H
O
F