Why do atoms have a covalent bond?

Answer 1

Covalent bonds are formed when atoms share electrons --- they both need the shared electron(s) to fill their outer electron shell. Ionic bonds are when one atom gives electron(s) to another atom --- the atom that has given the electron(s) has a positive charge and the atom that received the electron(s) has a negative charge

Answer 2

Elements form ionic or covalent compounds depending upon their valency.

for example :- All metals form ionic compounds generally as they are easily able to loose their electrons. Many non-metals gain these electrons and form ionic compound with the metals.

But many non-metals form covalent compounds by sharing their valence electrons with other non-metals. Most prominent being the carbon atom. Its very difficult for a carbon atom to gain or loose four electrons in its valence shell to form ionic compounds.

So, it forms covalent compounds by sharing its four electrons with other elements.

Answer 3

When the electronegativity difference between two atoms is below 2, then covalent bond is formed