Explain the difference between the valence electrons and the covalence of an element.

List the factors that determine the type of bond that will be formed between two atoms?

A chemical compound has the following Lewis notation:

a) How many valence electrons does element Y have?

b) What is the valency of element Y ?

c) What is the valency of element X ?

d) How many covalent bonds are there in the molecule?

e) Suggest a name for elements X and Y.

Why do only valence electrons involve in bond formation? Why not electron of inner shells? Explain.

Explain the formation of sodium chloride and calcium oxide on the basis of the concept of electron transfer from one atom to another atom.