For example, carbon atoms have six protons, hydrogen atoms have one and oxygen atoms have eight. The number of protons in an atom is unique to each element. Protons are about 99.86% as massive as neutrons (opens in new tab) according to the Jefferson Lab. Rutherford discovered them in experiments with cathode-ray tubes that were conducted between 19. Protons are positively charged particles found within atomic nuclei. These atoms will then decay into other elements, such as carbon-14 decaying into nitrogen-14. Some atomic nuclei are unstable because the binding force varies for different atoms based on the size of the nucleus. This force between the protons and neutrons overcomes the repulsive electrical force that would otherwise push the protons apart, according to the rules of electricity. The nucleus is held together by the strong force, one of the four basic forces in nature. The protons and neutrons that make up the nucleus are approximately the same mass (the proton is slightly less) and have the same angular momentum, or spin. Virtually all the mass of an atom resides in its nucleus, according to Chemistry LibreTexts (opens in new tab). He also theorized that there was a neutral particle within the nucleus, which James Chadwick, a British physicist and student of Rutherford's, was able to confirm in 1932. In 1920, Rutherford proposed the name proton for the positively charged particles of the atom. The nucleus was discovered in 1911 by Ernest Rutherford, a physicist from New Zealand, according to the American Institute of Physics (opens in new tab). Adding a proton to an atom makes a new element, while adding a neutron makes an isotope, or heavier version, of that atom. Atoms always have an equal number of protons and electrons, and the number of protons and neutrons is usually the same as well. However, one proton is about 1,835 times more massive than an electron. Protons and neutrons have approximately the same mass.

Atoms join together to form what