Quantities to specify “how much?”.
| Quantity or constant | Symbol | Definition (relating to specified component B) | SI unit | Note |
|---|---|---|---|---|
| 1. Typical entities are atoms, molecules, ions, and particles, such as microbiological colony forming units (CFU). 2. The fixed constants defining the SI are given in Table 1.9 of Section 1.8.5. They do not carry any measurement uncertainty. 3. The Ångström Å = 10−10 m is widely used but is not an SI unit. 4. The litre, symbol “L” or “l”, the dalton, symbol “Da”, the unified atomic mass unit, symbol “u”, are non-SI units accepted for use with the SI. Dalton may be combined with the SI prefixes given in Table 1.3. 5. Formula unit denotes an entity specified as a group of atoms. Note that ‘formula unit’ is not a unit. | ||||
| number of entities | N | 1 | 1 | |
| amount of substance, chemical amount | n |
| mol | |
| Avogadro constant NA = 6.02214076 × 1023 mol−1 | NA | N/n | mol−1 | 2 |
| mass | m | kg | ||
| molar mass | M | MB = m/nB | kg mol−1 | |
| length, distance | l, d, r | m | 3 | |
| area | A | m2 | ||
| volume | V | m3, l (L) | 4 | |
| atomic mass constant | mu | mu = ma(12C)/12 | kg | |
| unified atomic mass unit, dalton |
|
| kg | 4 |
| kg | 4 | |||
| atomic mass, mass of atom | ma | kg | ||
| relative atomic mass (historically: atomic weight) | Ar | Ar = ma/mu | 1 | |
| standard atomic weight65 of element E |  | 1 | ||
| atomic weight65 of an element E in a specific substance P | Ar(E, P) | 1 | ||
| mass of entity (molecule, formula unit) | mf | kg | 5 | |
| relative molecular mass (historically: molecular weight) | Mr | Mr = mf/mu | 1 | |
| charge number of ion B | zB | zB = QB/e | 1 | |
| Quantity or constant | Symbol | Definition (relating to specified component B) | SI unit | Note |
|---|---|---|---|---|
| 1. Typical entities are atoms, molecules, ions, and particles, such as microbiological colony forming units (CFU). 2. The fixed constants defining the SI are given in Table 1.9 of Section 1.8.5. They do not carry any measurement uncertainty. 3. The Ångström Å = 10−10 m is widely used but is not an SI unit. 4. The litre, symbol “L” or “l”, the dalton, symbol “Da”, the unified atomic mass unit, symbol “u”, are non-SI units accepted for use with the SI. Dalton may be combined with the SI prefixes given in Table 1.3. 5. Formula unit denotes an entity specified as a group of atoms. Note that ‘formula unit’ is not a unit. | ||||
| number of entities | N | 1 | 1 | |
| amount of substance, chemical amount | n |
| mol | |
| Avogadro constant NA = 6.02214076 × 1023 mol−1 | NA | N/n | mol−1 | 2 |
| mass | m | kg | ||
| molar mass | M | MB = m/nB | kg mol−1 | |
| length, distance | l, d, r | m | 3 | |
| area | A | m2 | ||
| volume | V | m3, l (L) | 4 | |
| atomic mass constant | mu | mu = ma(12C)/12 | kg | |
| unified atomic mass unit, dalton |
|
| kg | 4 |
| kg | 4 | |||
| atomic mass, mass of atom | ma | kg | ||
| relative atomic mass (historically: atomic weight) | Ar | Ar = ma/mu | 1 | |
| standard atomic weight65 of element E | | 1 | ||
| atomic weight65 of an element E in a specific substance P | Ar(E, P) | 1 | ||
| mass of entity (molecule, formula unit) | mf | kg | 5 | |
| relative molecular mass (historically: molecular weight) | Mr | Mr = mf/mu | 1 | |
| charge number of ion B | zB | zB = QB/e | 1 | |