Two Hydrogen atoms can also bond with two Oxygen atoms, making the formula H 2 O 2 . That's just one more Oxygen than water, but it is a totally different compound. You can see that each of the Oxygen atoms has eight electrons, and the two Hydrogens have two electrons each. You should know that even though there are two electrons involved in a bond, those electrons are used in different ways. Ionic bonds happen when electrons are given up by one atom to another.
Covalent bonds happen when electrons are shared by both atoms.
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