How many protons are in an oxygen atom?

There are always 8 protons in one oxygen atom. In one molecule of oxygen gas, which is O2, there are always 2 times 8 = 16 protons. In one molecule of ozone gas, which is O3, there are always 3 times 8 = 24 protons.

8 is the magic number of protons, so the oxygen nucleus is especially stable. This means that oxygen is not a good fuel for nuclear reactors. Nitrogen has 7 protons, which is not magic, so nitrogen is a much better fuel for a nuclear reactor.