Proton definition

prōtŏn
Frequency:
The stable, positively charged nucleon, having a mass 1,836 times that of an electron and being a baryon composed of two up quarks and one down quark. The proton is a basic component of all atomic nuclei and the nucleus of the protium isotope of hydrogen.
noun
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(particle physics) A nucleon carrying a positive charge equal to the negative charge of an electron and having a mass of c. 1.673 × 10-27 kg (c. 938.2796 MeV/c2, c. 1,836 times the mass of an electron): the number of protons in an atom determines the atomic number of a chemical element.
noun
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The definition of a proton is a particle with a positive charge that is in the nucleus of an atom.

An example of a proton is the single proton in the nucleus of a hydrogen atom.

noun
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A stable subatomic particle in the baryon family having a mass of 1.672 × 10&spminus;24 grams (1,836 times that of the electron) and a positive electric charge of approximately 1.602 × 10&spminus;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.
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(physics) Positively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element; the nucleus of the most common isotope of hydrogen; composed of two up quarks and a down quark.
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Other Word Forms

Noun

Singular:
proton
Plural:
protons

Origin of proton

  • From Greek prōton neuter of prōtos first per1 in Indo-European roots

    From American Heritage Dictionary of the English Language, 5th Edition

  • From Ancient Greek πρῶτον (prōton), neuter of πρῶτος (prōtos, “first")

    From Wiktionary