A neutral atom of oxygen-18 has 8 protons.
Oxygen is the element with atomic number 8, which means every oxygen atom, regardless of its isotope, has 8 protons in its nucleus. Isotopes like oxygen-18 refer to atoms that have the same number of protons but different numbers of neutrons. In the case of oxygen-18, it has 10 neutrons (18 total nucleons – 8 protons = 10 neutrons). However, it’s important to note that the proton count remains the same for all isotopes of oxygen, confirming that a neutral atom of oxygen-18 specifically contains 8 protons.