By Team Aakash Byju's
Can you guess the answer fore the given quiz? Guess the valency of an element whose atomic number is 15. 1. +1 2. -2 3. +3 4. -1
The answer for the quiz is C.
Let's take phosphorus whose atomic number is 15 and find its valency.
We know that the number of electrons that must be lost or gained by it to obtain a stable electron configuration.
The electronic configuration of Phosphorus is:
If you notice, it is easier for phosphorus to gain 3 electrons than to lose 5 electrons.
So, if the valency of phosphorus will be 3 if it is using only electrons from p.
If the electrons from both "s" and "p" are used, the valence of phosphorus will be 5.
Thus, the valencies of an element whose atomic number is 15 are 3 and 5.