Mercurous ion is written as `Hg_(2)^(2+)` whereas cuprous ion is written as `Cu^(+)` . Explain.

Answer

`Hg^(+)` has `[Xe]4f^(14)5d^(10)6s^(1)` configuration and thus `Hg^(+)` ion should be paramagnetic due to one unpaired electron but `Hg^(+)` ion show diamagnetic nature and for this it exits as `Hg_(2)^(2+)` by sharing of one electron each. Cuprous ions are diamagnetic with [Ar]3d^(10)` configuration and so written as `Cu^(+)`