Question

Aluminium and phosphorus are close to one another in the Periodic Table but the P3- ion is much larger than the Al3+ ion. Explain the reason for this change in size.

Answer 1

The P" ion has an electh arrangement of 2,8,8 ie three filled
electron energy level: The AP' ion has on electron
arrangement of 2,8 ie two filled electron energy levels. The
third electron energy level is further away from the nucleus
than the second and so the P" ion is the larger ion