It was assumed that the atom contained two protons instead of one.

The inner belt is the more dangerous one, containing energetic protons.

Molecules contain protons and electrons as part of their individual atoms.

Hydrogen-1 and helium-3 are the only stable nuclides that contain more protons than neutrons.

Nucleus: the central part of an atom that contains protons and neutrons.

Its nucleus contains 17 protons and 20 neutrons for a total of 37 nucleons.

The nucleus of the most common isotope of lead contains 82 protons, not 208.

Calcium-48 is a rare isotope of calcium containing 20 protons and 28 neutrons.

In Iron, atomic number 26, for instance, the nucleus contains 26 protons.

Beryllium's most common isotope is Be, which contains 4 protons and 5 neutrons.