Arrange the following isoelectronic species (O^(2-) , F^(-) , Na^+, Mg^(2+)) in order of: increasing ionic radius and

Arrange the following isoelectronic species (O^(2-) , F^(-) , Na^+, Mg

1.	Arrange the following isoelectronic species (O^(2-) , F^(-) , Na^+, Mg^(2+)) in order of: increasing ionic radius and
Answer» Solution :`MG^(2+) LT Na^(+) lt F^(-)lt O^(2-)` This ORDER can be justified on the basis of the fact that a negative anion is larger than its neutral atom due to a decrease in effective nuclear charge. As the VALENCE electrons now experience WEAKER attractions from the nucleus, its size must be largest. On the contrary,a cation will have smaller size than its neutral atom due to an increase in effective nuclear charge. Higher the positive charge, smaller the cation.