molecule (single particle)
Amount of substanceexact by definition
One molecule is 1/N_A moles, 1.66053907 × 10⁻²⁴ mol, and the value is exact because the Avogadro constant has been fixed at exactly 6.02214076 × 10²³ per mole since 2019. It lets a count of particles be entered where a formula wants an amount.
Watch out: The same entry serves atoms, ions, formula units and photons. Chemistry's "per particle" is whatever the equation is counting, and the conversion does not know which.
| 1 | 1.6605391e-24 |
Where the unit came from
The 2019 redefinition inverted the logic of the mole. It used to be the number of atoms in 12 grams of carbon-12, a quantity you had to measure; now it is a defined count, and the mass of 12 grams of carbon-12 is what carries the uncertainty instead.
One molecule (single particle) in every amount of substance unit
Solvers that use amount of substance