The oxygen atoms in \(\mathrm{O}_{2}\) participate in multiple bonding, whereas those in hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2},\) do not. (a) Draw Lewis structures for both molecules. (b) What is the hybridization of the oxygen atoms in each molecule? (c) Which molecule has the stronger \(\mathrm{O}-\mathrm{O}\) bond?

For \(\mathrm{O}_{2}\) molecule, each oxygen atom has 6 valence electrons. In order to achieve the full octet for both atoms, they will form a double bond by sharing two pairs of electrons. In case of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (hydrogen peroxide), it is a bit more complicated. Each oxygen atom has 6 valence electrons, and hydrogen atom has 1 valence electron. For the oxygen atoms to have a full octet, they will share one pair of electrons to form an oxygen-oxygen single bond. The remaining two pairs of electrons from each oxygen atom will form bonds with hydrogen atoms.

We can determine the hybridization of an atom by counting its number of sigma bonds and lone pairs; summing these values gives the steric number of the atom. The oxygen in the \(\mathrm{O}_{2}\) molecule has two sigma bonds (one double bond) and two lone pairs, so it has a steric number of 4 and hybridization of sp³. In \(\mathrm{H}_{2} \mathrm{O}_{2}\), each oxygen atom has one sigma bond with the other oxygen atom, two sigma bonds with hydrogen atoms, and one lone pair of electrons. So, each oxygen atom has a steric number of 4 and hybridization of sp³, too.

In the \(\mathrm{O}_{2}\) molecule, there is a double bond between the oxygen atoms, whereas in \(\mathrm{H}_{2} \mathrm{O}_{2}\) there is a single bond. In general, double bonds are stronger than single bonds because of the greater electron density in the bonding region. This means the \(\mathrm{O}-\mathrm{O}\) bond in \(\mathrm{O}_{2}\) is stronger than that in \(\mathrm{H}_{2} \mathrm{O}_{2}\). So, to summarize: (a) \(\mathrm{O}_{2}\) has a double bond between the oxygen atoms, and \(\mathrm{H}_{2} \mathrm{O}_{2}\) has a single O-O bond and each oxygen atom bonded to one hydrogen atom. (b) The oxygen atoms in both molecules have sp³ hybridization. (c) The \(\mathrm{O}-\mathrm{O}\) bond in the \(\mathrm{O}_{2}\) molecule is stronger than the bond in \(\mathrm{H}_{2} \mathrm{O}_{2}\).