What type of bonding will occur between magnesium atom and a oxygen atom?

A ionic bond will form. Magnesium will lose two electrons and the two chlorine atoms will pick up one atom each. It will become magnesium dichloride (MgCl2).

I believe that a polar - covalent bond will form. .3 to1.7 difference in electronegativity is polar covalent. and when you subtract the electronegativity of the two elements you get .5 and that falls in the polar covalent area.