IUPAC Gold Book - Physical constants

Physical constants - definitions

Symbols used	Definition
$Math - apply$	atomic mass constant
$Math - math$ $Math - math$	Avogadro constant
$Math - apply$	Bohr magneton
$Math - apply$ $Math - apply$ $Math - apply$	Bohr radius
$Math - apply$ $Math - apply$	Boltzmann constant
$Math - apply$ $Math - apply$	electron rest mass
$Math - math$	elementary charge
$Math - apply$	Faraday constant
$Math - math$	fine structure constant, $α$
$Math - apply$	gas constant
$Math - apply$	gravitational constant
$Math - apply$	Hartree energy
$Math - apply$	neutron rest mass
$Math - apply$	nuclear magneton
$Math - apply$	permeability of vacuum, $μ 0$
$Math - apply$ $Math - apply$	permittivity of vacuum
$Math - apply$	$h = 6.626 06896 33 × 10 −34 J s$ in Planck constant
$Math - apply$	$ℏ = h 2 π = 1.054 571 628 53 × 10 −34 J s$ in Planck constant
$Math - apply$	proton magnetic moment
$Math - apply$	proton rest mass
$Math - apply$	$c 1 = 2 π h c 0 2 = 3.741 7749 22 × 10 −16 W m 2$ in radiation constants
$Math - apply$	$c 2 = h c 0 k = 1.438 769 12 × 10 −2 m K$ in radiation constants
$Math - apply$	Rydberg constant
$Math - apply$ $Math - apply$	speed of light in a vacuum
$Math - apply$	Stefan–Boltzmann constant