Question

What is the electron configuration for `Al^(+3)` and `As^-3`?

Answer 1

We follow the standard electron counting scheme.

Explanation:

`Al^(3+), Z=13:` `1s^(2)2s^(2)2p^(6)` (the `3s` and `3p` electrons have been removed.

`As^(3-), Z=33:` `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(2)4p^(6)` (the `As^(3-)` ion thus has the same electronic configuration as `Kr`.