how do two atoms form an ionic bond how do two atoms form a covalent bond?

It is ionic if at least one of the atoms in the compound (usually the first) is a metal.

It is covalent if both of the atoms in the compound are non-metals.

ionic bond is formed when one atom transfers electrons to the other atom forming a + ion and a - ion which attract each other
eovalent bond is formed b the sharing of 1 or more electrons bt 2 atoms