Phosphorus and sulphur show multiple valency. Why do some elements show multiple valency? Discuss with your friends and teachers.

Explanation

1) For sulphur, the number of electrons in outer most orbit is 6.
2) Hence the valency should be `(8-6)=2.`
3) But sulphur exists in so many forms.
4) In the excited state, these 6 electrons also tend to participate in the bond formation.
5) Hence sometimes it shows the valency 6. Ex : `SO_(2), SO_(3),` etc.
6) Same situation happens for phosphorus. Ex : `PCl_(3), PCl_(5)`, etc.