Question

Among the following which is not paramagnetic?

(1) `Ne^(2+)`
(2) `Be^+`
(3) `Cl^-`
(4) `As^+`

Answer 1

`Cl^-` is Diamagnetic ... That is, all orbitals have paired electrons.

Explanation:

`Ne^o:[He]2s^(2)2p_x^2p_y^2p_z^2` => `Ne^+:[He]2s^(2)2p_x^2p_y^2p_z^1` + `e^-` (`2p_z` orbital is paramagnetic)

`Be^o:[He]2s^2` => `Be^+[He]2s^1` + `e^-` (`2s` orbital is paramagnetic).

`Cl^(o): [He]2s^(2)2p_x^2p_y^2p_z^1` + `e^-` => `Cl^(-): [He]2s^(2)2p_x^2p_y^2p_z^2` (All orbitals are filled (i.e., paired electrons) and therefore all diamagnetic (not paramagnetic).

`As ^o:[Ar]4s^"2"3d^"10"4p_x^1p_y^1p_z^1` =>

`As ^+:[Ar]4s^"2"3d^"10"4p_x^1p_y^1p_z^1` + `e^-` (all 4p orbitals are paramagnetic).