proton

[proh-ton]

noun

Physics, Chemistry.

1. a positively charged elementary particle that is a fundamental constituent of all atomic nuclei. It is the lightest and most stable baryon, having a charge equal in magnitude to that of the electron, a spin of ½, and a mass of 1.673 × 10 -27 kg. P

proton

/ ˈprəʊtɒn /

noun

1. 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 1/ 2

proton

1. 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.

2. See Table at subatomic particle

proton

1. An elementary particle with a positive charge, found in the nucleus of an atom.

Protons and neutrons make up most of an atom's mass.

A proton is over a thousand times heavier than an electron.

Other Word Forms

• protonic adjective

Word History and Origins

Origin of proton¹

Term first suggested in 1920 by English physicist Ernest Rutherford as noun use of Greek prôton, neuter of prôtos “first,” the proton being the constituent of hydrogen nuclei, and formed on the analogy of electron; first, electron

Word History and Origins

Origin of proton¹

C20: from Greek prōtos first

Example Sentences

Yet protons in the "knee" energy range are extremely rare, and satellite detectors have limited coverage, making such observations extraordinarily challenging.

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When astatine decays, it emits alpha particles -- tiny clusters made of two protons and two neutrons -- that can release powerful, localized bursts of energy.

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Jayich explained that MRI works by controlling the alignment and energy states of protons and detecting the signals they emit as they relax, forming an image of internal structures.

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At the center of each of those atoms lies the nucleus, a mash-up of even smaller particles called protons and neutrons.

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In the nucleus, the center of the atom, protons and neutrons are packed tightly.

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