Question

arrange these ions according to ionic radius.
largest radius
smallest radius
answer bank
na+
mg²+
n³-
o²-
f-

Explanation:

For isoelectronic ions (ions with the same number of electrons), the ionic radius decreases as the nuclear charge (atomic number of the parent atom) increases. The formula for nuclear charge is \(Z = \text{atomic number}\).

• For \(N^{3 -}\): \(Z=7\)
• For \(O^{2 -}\): \(Z = 8\)
• For \(F^{-}\): \(Z=9\)
• For \(Na^{+}\): \(Z = 11\)
• For \(Mg^{2+}\): \(Z=12\)

Since \(N^{3 -}\) has the lowest nuclear charge among these isoelectronic ions (\(1s^{2}2s^{2}2p^{6}\) electron - configuration for all), it will have the largest ionic radius as the electrons are less tightly held. As the nuclear charge increases (\(N^{3-}

Answer:

Largest radius: \(N^{3 -}\), then \(O^{2 -}\), then \(F^{-}\), then \(Na^{+}\), Smallest radius: \(Mg^{2+}\)