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  • Arrange the following in increasing order of their ionic radii: Mg2+, Na+, F-,O2-,N3-.Opt

Arrange the following in increasing order of their ionic radii:
Mg2+, Na+, F-,O2-,N3-.

Option: 1

Mg2+< Na+< F-<O2-<N3-


Option: 2

Mg2+>Na+> F->O2->N3-


Option: 3

Na+<O2-<N3-< Na+<Mg2+


Option: 4

Na+>O2->N3-> Na+>Mg2+


Answers (1)

best_answer

Variation of Atomic Radii and ionic radii -

Comparison of the ionic radii and atomic radii

Variation in a Group

 

In moving from top to bottom in a group, the number of shells increases due to which the atomic size increases. 

  • The size of the cation is always smaller than its parent atom. In the case of cations, the number of electrons in the ion decrease and the nuclear charge remains the same, thus the effective nuclear charge increases and the size decreases.

  • Thus, the size of cation ∝ 1/Zeff 

  • M+3 < M+2 < M+ < M 

  • The size of the anion is always greater than its parent atom. In the case of anions, the number of electrons in the ion increase and the nuclear charge remain the same, thus the effective nuclear charge decreases and the size increases.

  • Thus, size of anion ∝ 1/Zeff 

  • M-3 > M-2 > M- > M

-

These are isoelectronic species having the same number of electrons but different number of protons. So for this case, we don’t have to focus on period and group. Remember that size is inversely proportional to the atomic number(Z).

Therefore, option(1) is correct

Posted by

manish painkra

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