Question

Arrange the following ions in the increasing order of their size: `Be^(2+), CI^(-), S^(2-), Na^(+), Mg^(2+), Br^(-1)`?

Answer 1

Correct Answer - `Be^(2+) lt Mg^(2+) lt Na^(2+) lt CI^(-) lt S^(2-) lt Br^(-)`
`Be^(2+)` is smaller than `Mg^(2+)` as `Be^(2+)` has one sheel where as `Mg^(2+)` has two sheels.
`Mg^(2+)` and `Na^(+)` are isoelectronic species: Ionic radius `prop 1//nuclear` charge.
`CI^(-)` and `S^(2-)` are isoelectronic species: Ionic radius `prop 1//nuclear` charge.
`CI^(-)` is smaller than `BI^(-)` as `CI^(-)` has three shells where as `BI^(-)` has four shells.