Electronic configuration of P = 2, 8, 5
P atom gains 3e– to form P3-
∴ P3- has configuration = 2, 8, (5 + 3) = 2, 8, 8
Electronic configuration of P = 2, 8, 5
P atom gains 3e– to form P3-
∴ P3- has configuration = 2, 8, (5 + 3) = 2, 8, 8
| Elements | Protons | Electrons | Neutrons | Atomic Number | Mass Number |
| A | – | – | 10 | 8 | – |
| B | 15 | – | – | – | 31 |
| C | 1 | – | – | – | 3 |
| D | – | 11 | 12 | – | – |
| X | Y | |
| Protons | 8 | 8 |
| Neutrons | 8 | 10 |