Oxygen has an atomic number of 8 and an atomic mass of approximately 16.

Here's what these numbers mean:

* Atomic Number: This represents the number of protons in an atom's nucleus. All oxygen atoms have 8 protons, which defines them as oxygen.

* Atomic Mass: This is the average weight of an atom, taking into account the different isotopes (atoms with the same number of protons but different numbers of neutrons). The most common isotope of oxygen has 8 protons and 8 neutrons, giving it a mass number of 16. However, there are other isotopes with different numbers of neutrons, so the atomic mass is a weighted average, which is slightly higher than 16.

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