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The mass number (M) of an atom is equal to the number of protons and neutrons of the atom. For example carbon-12 has 6 protons and 6 neutrons, thus, its mass number M = p + n, M = 6 + 6 = 12. The chlorine isotope Cl-35 has 17 protons and 18 neutrons. Its mass number MCl-35 = 17 + 18 = 35. The Cl-37 isotope has 17 protons and 20 neutrons, MCl-37 = 17 + 20 = 37. However, the atomic weight of naturally occuring chlorine is (35 x 0.7553) + (37 x 0.2447) = 35.5 amu , where 75.53% and 24.47% are the natural abundances of the Cl-35 and Cl-37 isotopes.
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The number of protons plus neutrons in the nucleus of a particular isotope of an element.
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total mass of an atom; the sum of neutrons and protons.
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Mass number (A) is a characteristic property of a specific isotope of an element, equal to the sum of the number of protons and neutrons in the nucleus.
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Sum of the number of neutrons (n) and the number of protons (p) in the nucleus of an atom. It gives the approximate mass of that atom. Compare atomic number.
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The mass number, , is the sum of the number of protons and neutrons in a nucleus. It is very close to the weight of that nucleus in atomic mass units.
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The mass number of an atom is the total number of its nuclear constituents, or nucleons, as the protons and neutrons are collectively called.
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Mass number is the average number of nucleons found in a large sample of an element. Naturally occurring chlorine exists in the form of two isotopes Cl37 (25%) and Cl35 (75%). Therefore the 'average' mass of a chlorine atom is 35.5. Chemists use mass number because they deal with large quantities of atoms. Physicists prefer the term nucleon number and deal with individual isotopes rather than the naturally occurring mixture of them.
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The sum of the neutrons and protons in a nucleus. It is the nearest whole number to an atom's atomic weight. For instance, the mass number of 235U is 235.
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The mass number of an atom is equal to the number of protons plus the number of neutrons in that atom. Atomic Structure
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The sum of the numbers of protons and neutrons in an atom; an integer.
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The sum of the number of neutrons and protons in a nucleus.
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The number of protons and neutrons in an atom.
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The mass number of an atom is the number of protons and neutrons in the nucleus of the atom.
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The total number of protons and neutrons in the nucleus: A=Z+N. This is also the total nucleon number of the nucleus.
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The total number of protons and neutrons in an atomic nucleus. Also called nucleon number. Radioactivity
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Total number of neutrons and protons in the nucleus of an atom. Approximate measure of the mass of an atom. Also see atomic number.
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The number of protons plus neutrons in the nucleus of an atom. Symbol
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The mass number (A) of an element is the number of protons plus the number of neutrons in the nucleus of the atom. Classifying materials
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The mass number (A), also called atomic mass number or nucleon number, is the number of nucleons (protons and neutrons) in an atomic nucleus. The mass number is unique for each isotope of an element and is written either after the element name or as a superscript to the left of an element's symbol. For example, carbon-12 (12C) has 6 protons and 6 neutrons.
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