Covalent bond or ionic bond

[space stuff]

We are told in 10th class that electropositive (like alkali metals and alkaline earth metals) elements and electronegative elements (like halogens) form ionic compounds such as sodium chloride. But now in 11th class we are told that lithium and beryllium (which are too alkali and alkaline earth metals respectively) and some more metals do form covalent compounds. Why should lithium form a covalent bond with chlorine if lithium can donate one electron and chlorine can gain one electron easily to form an ionic bond ? Its a bit confusing...

Edited May 21, 2012 by Sarthak Sahu

[Siddarth]

Any bond has a certain ionic and covalent character to it. The majority decides whether it is a ionic or covalent bond.

 

Alkali metals tend to have a greater ionic character to their bonds.