ISO 31-8

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.

Quantities and units

Quantity Unit Remarks
Name Symbol Definition Name Symbol
relative atomic mass Ar Ratio of the average mass per atom of an element to 1/12 of the mass of an atom of the nuclide 12C one 1 Formerly called atomic/molecular weight.
Example: Ar(Cl) = 35.453.
Both quantities depend on the nuclidic composition.
relative molecular mass Mr Ratio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of an atom of the nuclide 12C
number of molecules or other elementary entities N Number of molecules or other elementary entities in a system one 1
amount of substance n, (ν) mole mol The 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 page was last updated at 2024-02-07 23:59 UTC. Update now. View original page.

All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License.


Top

If mathematical, chemical, physical and other formulas are not displayed correctly on this page, please useFirefox or Safari