Question

An element X combines with oxygen to form an oxide XO. This oxide is electrically conducting.

(a) How many electrons would be there in the outermost shell of the element X?
(b) To which group of the periodic tables does the element X belong?
(c) Write the formula of the compound formed when X reacts with chlorine.

Answer 1

(a) The element X is electrically conductive. Therefore, it is a metal. In the case of compound XO, both the elements are divalent, since the valency of oxygen is 2. Therefore, the valency of X should also be 2.

(b) We can conclude that X belongs to Group 2. Since the valency of the element X is 2 and it is showing electrical conductivity, therefore, it is a metal.

(c) The formula of the compound formed is XCl_2, since chlorine is a group 17 element with 7 valence electrons. It has a valency of 1. Therefore, when one atom of X combines with two atoms of chlorine (Cl), an ionic compound of the formula XCl₂ is formed.