Which of the following compounds present exceptions to the octet rule ?

Question

a) PF5


b) BCl3


c) XeF6


d) ClF3


e) NF3

Answer 1

for P: [Ne] 3s2 3p3
for F: 1s2 2s2 2p5
PF5 conforms (P lost 5, F accept 1 each)

for B: 1s2 2s2 2p1
for Cl: [Ne] 3s2 3p5
BCl3 conforms (B lost 3, Cl accept 1 each)

for Xe: [Kr] 4d10 5s2 5p6
for F: 1s2 2s2 2p5
XeF6 exception (Xe already had 8)

for Cl: [Ne] 3s2 3p5
for F: 1s2 2s2 2p5
ClF3 exception (Cl had 7 only share 3)

for N: 1s2 2s2 2p3
for F: 1s2 2s2 2p5
NF3 exception (N had 5 only share 3)

Answer 2

PF5, BCl3, and XeF6