Question

Which following pairs of atoms, have a lower electron affinity? a) Ca,K b) I,F c) Li, Ra. I seriously don't know anything about electron affinity all ik that it can buy another element

Answer 1

$\bold{ELECTRON \: AFFINITY}$

It is the amount of energy released when an atom in gaseous state accepts an electron to form an anion.

▶Its dependence :-

✳A small atom takes up electrons readily rather than a large atom so atomic size decreases electron affinity increases.

✳Nuclear charge increases so the tendency of accepting a electron increases so electron affinity increases.

◼Across a period

Atomic radius decreases so electron affinity increases and nuclear charge increases so electron affinity increases.

Overall, electron affinity increases.

◼Across a group

Atomic radius increases so electron affinity should decrease.

Nuclear charge increases so electron affinity should increase.

Since atomic radii dominates over nuclear charge so overall it decreases.

◼For K and Ca

The lies in the group 1 and 2 and in period 4 so they have least electron affinity.

◼For I and F

They lies in group 17 and in period 2 and 5 , so as they lies in end of period so they have most electron affinity.

◼For Li and Ra

They lies in group 1 and 2 and in period 2 and 7 ,so Li will have a low affinity but Ra will have the least reactivity among all given elements in the question.

$\bold{So \: option \: C \: will have \: least, \: ELECTRON \: AFFINITY}$