Which has the largest ionization energy ? F+ or Ne? And, which has a greater atomic radius? Cl + or Cl +2?

F⁺ has the greater ionization energy than Ne.

The electronic configuration of F⁺ (Z = 9) : 1s² 2s² 2p⁴
The electronic configuration of Ne (Z = 10) : 1s² 2s² 2p⁶
F⁺ and Ne have similar nuclear charge. In ionization, a 2p electron is removed from both F⁺ and Ne.

F⁺(g) → F²⁺(g) + e⁻ …. ΔH = Ionization energy of F⁺
Ne(g) → Ne⁺(g) + e⁻ …. ΔH = Ionization energy of Ne

Refer to the product sides of the above two equations. In ionization of F⁺, energy is needed to separate an electron and a doubly-positively-charged ion (F²⁺). In ionization of Ne, energy is needed to separate an electron and a singly-charged-positive ion (Ne⁺). Obviously, the former needs more energy.


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Cl⁺ has a greater atomic radius than Cl²⁺.

The electronic configuration of Cl⁺ (Z = 17) : 1s² 2s² 2p⁶ 3s² 3p⁴
The electronic configuration of Cl²⁺ (Z = 17) : 1s² 2s² 2p⁶ 3s² 3p³

Both Cl⁺ and Cl²⁺ have 3 filled electronic shells. Cl⁺ has 1 less electron than Cl²⁺.

In Cl⁺, 17 nuclear charges attract 16 electrons. In Cl²⁺, 17 nuclear charges attract 15 electrons. The electrons in the outermost shell of Cl⁺ experience smaller attractions than those of Cl²⁺. Besides, the greater number of electrons in Cl⁺ leads to a greater repulsion between electrons than Cl²⁺. Therefore, Cl⁺ has a greater atomic radius than Cl²⁺.

F+ Cl+