Question

A. Give one word or a phrase for the following.
(i) The energy released when an electron is added to a neutral gaseous isolated atom to form a negatively charged ion.
(ii) Process of formation of ions from molecules which are not in ionic state.

B. Arrange the following as per the the instruction given in the brackets:
(i) He, Ar, Ne (In the increasing order of the number of electron shells)
(ii) K, Pb, Ca , Zn (In the increasing order of the reactivity)
(iii) Na, K, Li (In the increasing order of atomic size)

Answer 1

A. (i) Electron affinity
(ii) Ionisation

B. (i) When we go down the group in the periodic table, the electron shells are added to the elements. We can also say that, in successive periods, the electron shell number increases by one. Hence the order of elements according to the increase in number of electron shells is as follows, He < Ne < Ar.

(ii) The reactivity series of metals, also known as the activity series, refers to the arrangement of metals in the descending order of their reactivities.
So, the correct order is: Pb < Zn < Ca < K.


(iii) We know that atomic size increases from right to left and from top to bottom in the Periodic Table. So the correct order of atomic radius is Li < Na < K.