Физикалық химия және молекулалық физика терминдері мен бірліктері (ISO 31-8)

Part of international standard ISO 31

ISO 31 8 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to physical chemistry and molecular physics.

Quantity Unit RemarksNameSymbolDefinitionNameSymbolrelative atomic massArRatio of the average mass per atom of an element to 1/12 of the mass of an atom of the nuclide 12Cone1Formerly called atomic/molecular weight. Example: Ar(Cl) = 35.453. Both quantities depend on the nuclidic composition. relative molecular massMrRatio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of an atom of the nuclide 12Cnumber of molecules or other elementary entitiesNNumber of molecules or other elementary entities in a systemone1amount of substancen, (ν) molemolThe mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of 12C. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specific groups of such particles. The definition applies to unbound atoms of 12C, at rest and in their ground state

This annex contains a list of elements by atomic number, giving the names and standard symbols of the chemical elements from atomic number 1 (hydrogen, H) to 109 (unnilennium, Une). The list given in ISO 31 8:1992 was quoted from the 1998 IUPAC "Green Book" Quantities, Units and Symbols in Physical Chemistry and adds in some cases in parentheses the Latin name for information, where the standard symbol has no relation to the English name of the element. Since the 1992 edition of the standard was published, some elements with atomic number above 103 have been discovered and renamed.