mass number

mass number
the integer nearest in value to the atomic weight of an atom and equal to the number of nucleons in the nucleus of the atom. Symbol: A
[1920-25]

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      in nuclear physics, the sum of the numbers of protons and neutrons present in the nucleus of an atom. The mass number is commonly cited in distinguishing among the isotopes of an element, all of which have the same atomic number (number of protons) and are represented by the same literal symbol; for example, the two best known isotopes of uranium (those with mass numbers 235 and 238) are designated uranium-235 (symbolized 235U) and uranium-238 (238U).

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Universalium. 2010.

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  • mass number — n an integer that approximates the mass of an isotope and that designates the number of nucleons in the nucleus <the symbol for carbon of mass number 14 is 14C or C14> compare ATOMIC MASS * * * (A) the number of nucleons (protons plus… …   Medical dictionary

  • mass number — n. Physics Chem. the number of neutrons and protons in the nucleus of an atom: the approximate mass of a given nucleus is obtained by multiplying the mass number by the fundamental unit of mass, 1.6605 × 10 24 grams (1/ 12 the mass of C12 atom) …   English World dictionary

  • mass number — ► NOUN Physics ▪ the total number of protons and neutrons in a nucleus …   English terms dictionary

  • Mass number — The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical… …   Wikipedia

  • mass number — noun the sum of the number of neutrons and protons in an atomic nucleus • Syn: ↑nucleon number • Hypernyms: ↑mass unit * * * ˈmass number 7 [mass number] noun …   Useful english dictionary

  • mass number — masės skaičius statusas T sritis Standartizacija ir metrologija apibrėžtis Atomo branduolio nukleonų skaičius. atitikmenys: angl. mass number; nuclear number; nucleon number vok. Massenzahl, f; Nukleonenzahl, f rus. массовое число, n; число… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • mass number — masės skaičius statusas T sritis chemija apibrėžtis Atomo branduolio nukleonų skaičius. atitikmenys: angl. mass number; nuclear number; nucleon number rus. массовое число …   Chemijos terminų aiškinamasis žodynas

  • mass number — masės skaičius statusas T sritis fizika atitikmenys: angl. mass number; nuclear number; nucleon number vok. Massenzahl, f; Massezahl, f; Nukleonenzahl, f rus. массовое число, n pranc. nombre de masse, m; nombre de nucléons, m …   Fizikos terminų žodynas

  • mass number — mass′ num ber n. phs the number of nucleons in an atomic or isotopic nucleus Symbol: A II, 8) • Etymology: 1920–25 …   From formal English to slang

  • mass number — noun Date: 1923 an integer that approximates the mass of an isotope and designates the number of nucleons in the nucleus …   New Collegiate Dictionary

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