# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 4 Search : atomic mass
 atomic mass   جرم ِ اتمی   jerm-e atomi (#)Fr.: masse atomique   The mass of a single atom, when the atom is at rest at its lowest energy level (→ ground state). Because a → chemical element may exist as various → isotopes, possessing different numbers of neutrons in their atomic nuclei, atomic mass is calculated for each isotope separately. Atomic mass is most often expressed in unified → atomic mass units, where one unified atomic mass unit is defined as one-twelfth the mass of a single atom of the carbon-12 isotope.→ atomic; → mass. atomic mass number (A-number)   عدد ِ جرم ِ اتمی   adad-e jerm-e atomi (#)Fr.: nombre de masse atomique   The total number of → protons and → neutrons in the → nucleus of an → atom (symbol A). For example, Oxygen-16 has a mass number of sixteen, because it has eight protons and eight neutrons.→ atomic; → mass; → number. atomic mass unit (amu)   یکای ِ جرم ِ اتمی   yekâ-ye jerm-e atomi (#)Fr.: unité de masse atomique   A unit of mass used for atoms and molecules, equal to 1/12 of the mass of an atom of carbon-12 (including orbital electrons). It is equal to 1.660 33 × 10-24 g.→ atomic; → mass; → unit. relative atomic mass   جرم ِ اتمی ِ بازانی   jerm-e atomi-ye bâzâniFr.: masse atomique relative   The ratio of the mass of an atom of the → chemical element to one-twelfth the mass of an atom of carbon-12. Because an element in nature is usually a mixture of isotopes, the relative atomic mass is also the weighted mean of the atomic masses of all the atoms in a particular sample of the element, weighted by isotopic abundance. In this sense, relative atomic mass was once known as → atomic weight.→ relative; → atomic; → mass.