|a stable, positively charged elementary particle, found in atomic nuclei in numbers equal to the atomic number of the element. It is a baryon with a charge of 1.602176462 × 10--19 coulomb, a rest mass of 1.672 62159 × 10--27 kilogram, and spin ½|
|[C20: from Greek prōtos first]|
proton pro·ton (prō'tŏn')
A stable, positively charged subatomic particle in the baryon family having a mass 1,836 times that of the electron.
|proton (prō'tŏn') Pronunciation Key
A stable subatomic particle in the baryon family having a mass of 1.672 × 10-24 grams (1,836 times that of the electron) and a positive electric charge of approximately 1.602 × 10-19 coulombs. Protons make up part of the nucleus of all atoms except hydrogen, whose nucleus consists of a single proton. In neutral atoms, the number of protons is the same as the number of electrons. In positively charged atoms, the number of protons is greater than the number of electrons, and in negatively charged atoms electrons outnumber protons. Protons are believed to be composed of two up quarks and one down quark. See Table at subatomic particle.