Question

What is the electron configuration using core notation for `Se^(2-)`?

Answer 1

`[Kr]`

Explanation:

The atomic No. of Se is 34
`Se^"2-"` has 34+2 = 36 electrons

Electronic configuration of `Se` in
Normal Notation
`1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^4`
Electronic configuration of `Se^(2-)` in
Normal Notation
`1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6`

In core notation it is

Krypton core i.e.`[Kr]`