Question

Is the radius of an ion always larger than the atomic radius of the original atom?

Answer 1

Absolutely not! Consider oxidation reactions of metals........

Explanation:

Consider oxidation reactions of the alkali metals:

`Na(s) rarr Na^+ + e^-`

We have removed the valence electron of an alkali metal. The ion, the oxidation product is MUCH smaller. TO illustrate the ionic radius of sodium ion in sodium chloride is `1.16xx10^-10*m`. The metallic radius of sodium metal is `1.80xx10^-10*m`.

(Note that I use `10^-10*m` units because the `"Angstrom"` is the standard unit for crystallography, tho I cannot find the proper symbol, a capital A with a circle hat.)

Of course reduction of a non-metal to give an anion, will give a larger ionic radius than the atomic radius. Why so?