Consider the following species:
`N^(3-)`,`O^(2-)`,`F^(ө)`,`Na^(o+)`,`Mg^(2+)` and `Al^(3+)`
a. What is common in them?
b. Arrange them in the order of increasing ionic radii.

Explanation

(a) All these ions have same number (10) of electrons. Therefore, these are also called isoelectronic species.
(b) Since the number of electrons are same, the ionic size decreaases with increase in nuclear charge. Therefore, the ions can be arranged in increasing order of ionic radii as
` Al ^(3+) lt Mg ^(2+) lt Na ^(+) lt F ^(-) lt O ^(2-) lt N^(3-)`