Question

What is different between an ionic bond and a covalent bond?

Answer 1

see below

Explanation:

Ionic bonds are bonds between two elements who has a large difference in electronegativity. For instance Sodium chloride: `NaCl.`
Sodium have a low electronegativity and chloride have a very high electronegativity.

Covalent bonds are bonds between elements both with high electronegativity. For instance CO2. Oxygen have a high electronegativity and carbon have a electronegativity in approx the middle of the scale.

As a rule of thumb you can think of it as, the non metal elements forming molecules, for instance `NH_3`, `CO_2` and so on, would form covalent bonds.
All metals (for the most) bonding with a non metal forms an ionic bond: `MgCl_2`, `ZnO` etc.