Electron molar mass

$M(e)$ = 5.485 799 0962(17) × 10⁻⁷ kg mol⁻¹

Value: 5.485 799 0962 × 10⁻⁷ kg mol⁻¹
Standard uncertainty: 1.7 × 10⁻¹⁶ kg mol⁻¹
Relative uncertainty: 3.1 × 10⁻¹⁰ (310 parts per trillion)
Status: Measured
Symbol: $M(e)$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# electron molar mass, CODATA 2022 (NIST)
electron_molar_mass = 5.4857990962e-7  # kg mol^-1, standard uncertainty 1.7e-16

# SciPy: scipy.constants.physical_constants['electron molar mass']

What it is

The mass of one mole of electrons (electron), in kilograms per mole.

How the value changed, 1998–2022

Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).

Relative uncertainty

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	5.485 799 0962(17) × 10⁻⁷	3.1 × 10⁻¹⁰	+4.4 σ of 2018
2018	5.485 799 0888(17) × 10⁻⁷	3.1 × 10⁻¹⁰	−11.9 σ of 2014
2014	5.485 799 090 70(16) × 10⁻⁷	2.9 × 10⁻¹¹	−1.8 σ of 2010
2010	5.485 799 0946(22) × 10⁻⁷	4.0 × 10⁻¹⁰	+0.1 σ of 2006
2006	5.485 799 0943(23) × 10⁻⁷	4.2 × 10⁻¹⁰	−0.1 σ of 2002
2002	5.485 799 0945(24) × 10⁻⁷	4.4 × 10⁻¹⁰	−1.3 σ of 1998
1998	5.485 799 110(12) × 10⁻⁷	2.2 × 10⁻⁹

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).