A proton, otherwise known as the hydrogen ion is a subatomic particle that is found in the nucleus of an atom; protons have an elementary charge of +1 and there can be one or more of them in the atom along with neutrons. A proton is made up of two up quarks and one down quark and is stable on its own and its quarks are held in place by a strong force supplied by gluon exchange particles.
The discovery of the proton is attributed to Ernest Rutherford in 1919 but the discovery of the proton was a gradual process based on the work of at least three physicists: Thomson, Rutherford and Chadwick, so none of the three are solely responsible for the proton’s discovery, however it was Rutherford who first classified the proton and so he is considered the person who discovered it but it was a series of discoveries between Thomson’s discovery of the electron in 1897, Rutherford’s discovery of the nucleus in 1911, and Chadwick’s discovery of the neutron in 1932 that led to the official discovery of the proton when physicists discovered that the nucleus contained positively charged elements.
First was the discovery of the electron which led physicists to realize that an atom had to contain positive charges to balance the negative charges of the electrons and make the atoms electrically neutral. Then Rutherford’s discovery of the nucleus showed physicists that the positive charges did not run through the entire atom but were concentrated in just a small area. Then in 1919 Rutherford further discovered that striking an element with energetic alpha particles would change it and the discovery of the proton was underway.
A number of experiments were carried out by Rutherford and other physicists in the early 1920s and it was found that in every experiment hydrogen nuclei were emitted during the process. Rutherford’s experiments consisted of shooting alpha particles into nitrogen gas and while doing this he noticed that scintillation detectors were showing hydrogen nuclei signatures; Rutherford concluded that the hydrogen must have come from the nitrogen and therefore nitrogen must be made up of hydrogen nuclei.
Next Rutherford started shooting alpha particles towards neon particles and concluded during these experiments that the hydrogen element had to be the building blocks of atoms; these experiments showed physicists that the hydrogen nucleus was a fundamental element in the atomic structure and by comparing nuclear masses to their charges it was discovered that a nucleus’s positive charges were related to an integer number of hydrogen nuclei. By the latter part of the 1920s hydrogen nuclei were regularly called protons and the term seems to have been originally coined by Rutherford, hence he is considered its discoverer and the ‘father of nuclear physics.’
All of Rutherford’s experiments involved atom transmuting and the end result was always hydrogen nuclei emission, and the fact that hydrogen has an atomic number of 1 further strengthened the point that the hydrogen nucleus played a major role and was a fundamental particle of the atom.