Question

Which of the following molecules is exception to octet rule

pcl5, cocl2, bcl3, ccl4

Answer 1

1) PCl5

P has 5 valence electrons.

It receives 5 more shared electrons from Cl.

So, it has 10 electrons now and hence it is an exception to octet rule

2)

CoCl2 is ionic compound

Co2+ has noble gas configuration

Cl- has noble gas configuration

This is not an exception

3)

B has 3 valence electrons.

It receives 3 more shared electrons from Cl.

So, it has 6 electrons now and hence it is an exception to octet rule

4)

C has 4 valence electrons.

It receives 4 more shared electrons from Cl.

So, it has 8 electrons now.

This is not an exception

Answer: PCl5, BCl3