A positively charged particle, denoted with the letter p, proton is a subatomic particle found within an atom’s nucleus, along with neutron(s). Having a mass of 1.6727 x 10-24, a proton weighs lesser than a neutron, but is much heavier than an electron – 1836 times heavier, to be precise. It has a radius of 0.84 femtometers, which is 0.84 × 10-15 meters.

Image credit: Flickr
Image credit: Flickr

The number of protons remains constant within different versions of the same atom – called isotopes – and which gives an atom its identity, referred to as atomic number, in the periodic table. Until the discovery of quarks, protons were considered the smallest subatomic particles. Post quark revelation, it was found a proton has one down (negative) quark and two up (positive) quarks. This gives a proton a net positive charge.

Similar to a neutron, even protons can step out of an atom’s nucleus and acquire potentially dangerous traits. But unlike neutrons, protons have an electric charge (positive) and could be further influenced by magnetic and/or electric fields.

Proton Discovery

Proton was discovered in 1911 by Ernest Rutherford. This finding was confirmed in 1913 by Henry Moseley. In 1919, Rutherford conducted an experiment wherein he fired helium atoms into nitrogen gas. The hydrogen nuclei’s characteristic trait was produced, with Rutherford concluding that a hydrogen atom nucleus consists of an elementary particle, later referred to as proton. It was proposed all atoms nuclei had proton(s). Rutherford was therefore credited with having discovered proton.