Question

(i) For each of the following pairs, predict which one has greater ionization energy and greater electron affinity ? 

(a) 1,1^– (b) B, C (c) Li, Li⁺

(ii) Select the correct order of radii of three species : Ca, Ca⁺ and Ca²⁺ : 

(a) Ca > Ca⁺ > Ca²⁺ 

 (b) Ca²⁺ > Ca⁺ > Ca 

(c) Ca⁺ > Ca > Ca²⁺ 

 (d) Ca⁺ > Ca²⁺ > Ca

Assign suitable reason.

Answer 1

Ionisation Energy	Electron affinity
(a) I- > I	(i) I > I-
(b) C > B	(ii) C > B
(c) Li+ > Li	(iii) Li  > Li+

(ii) The correct order of radii is (a), i.e., Ca > Ca⁺ > Ca^{2+ .}

 This is because due to the loss of electron, the effective nuclear charge per electron increases, the electrons are more strongly attracted and pulled towards the nucleus. This causes a decrease in the size of the positive ion.