It is a sub atomic particle, with a positive elemental charge, opposite to the electron and a mass 1836 times higher. The number of protons is the crucial data to determine the atomic number. The life expectancy of a proton is at least 10, 35 years, considering a stable particle; still, some scientists say that, at the end of its days, it can disintegrate into other particles. Its composition consists of two up quarks and one down quark, according to quantum chromodynamics.
It was discovered mainly by Ernest Rutherford, who detailed the moment when alpha particles were fired with nitrogen gas, scintillation detectors showed the signs of nitrogen nuclei, that is, the nucleus was made up of protons. Originally it was believed that it was an elementary particle, but in the year 1970 it was proved that it was a particle composed of three elementary spin particles. When fused with the neutron, they become nucleons, and make up the nucleus of atoms.
When they experience a great nuclear force they are called hadrons, and from the classification of these, they are called baryons, and they are considered the lightest. Although numerous tests have been carried out the spontaneous decay of a free proton has not yet been observed.
The proton is characterized by having a positive charge, but there is also an antiproton, which is an antiparticle, that is, a proton but with a negative charge. It is a particle that is stable in vacuum and does not disintegrate spontaneously. It was discovered in 1955, by Emilio segre and Owen Chamberlain, from the University of California. When colliding with a proton they become mesons, and the life of these particles is very short.
