Question

Consider the following elements:
Ca, Cl, Na, I, Li, Ba, Sr, K, Br

Separate these elements into three groups (families) of similar properties. State one property in each case on the basis of which you have made your choice.

Answer 1

(i) Lithium (Li), sodium (Na) and potassium (K) are three metals of group 1 having a valency of 1.
(ii) Calcium (Ca), strontium (Sr) and barium (Ba) are three metals of group 2 having a valency of 2.
(iii) Chlorine (Cl), bromine(Br) and iodine (I) are three non-metals of group 17 which are known as halogens, and have seven valence electrons.