Question

An element X from group 2 of the periodic table reacts with an element Y from group 17 to form a compound.

(a) What is the nature of the compound formed?

(b) State whether the compound formed will conduct electricity or not.

(c) Give the formula of the compound formed.

(d) What is the valency of element X?

(e) How many electrons are there in the outermost shell of an atom of element Y?

Answer 1

(a) The resulting compound is an ionic compound since the elements of group 2 are metals and those of group 17, non-metals. When a metal reacts with a non-metal, electrons get transferred from the metallic atoms to the non-metallic atoms, and an ionic bond is formed.

(b) Yes, it will conduct electricity because an ionic compound has formed.

(c) Element X belongs to group 2 and its valency is 2. Element Y is from group 17 and its valency is 1. So, one atom of X combines with two atoms of Y to give a compound of the formula $X{Y}_2$.

(d) The valency of the element X is 2 because it belongs to group 2.

(e) Group 17 elements have seven valence electrons in their atoms.
Group number = No. of valence electrons + 10
No. of valence electrons = Group number - 10
= 17 - 10 = 7.