How many protons are in the nucleus of an atom of oxygen?
The atomic number tells us how many protons are in the nucleus for any given element.
Oxygen is atomic number 8.
Therefore, its nucleus contains 8 protons.
Protons are positively charged. One proton has a charge of
So the atomic number not only tells us the number of protons in an atom, but also the number of electrons.
Oxygen has 8 protons, and 8 electrons.