Question

The elements Li(Z = 3), Na (Z = 11) and K (Z = 19) belong to group 1.

(i) Predict the periods they belong.

(ii) Which one of them is least reactive ?

(iii) Which one of them has the largest atomic radius ?

Give reason to justify.

Answer 1

(i) The Period number to which these elements belong are

Li=2^nd Period

Na =3^rd Period

K= 4^th Period

(ii) In a Group the chemical reactivity of metals from top to bottom increases. Lithium is least reactive.

(iii) Down the group the number of shells increases, So the atomic radius also increases. The element with the largest atomic radius is Potassium.