Fundamental Constants

 

Quantity	Symbol	Value
Atomic mass unit	u	1.660 538 782(83)×10−27kg
Avogadro’s number	NA	6.02214076×1023reciprocal mole(mol–1)
Bohr magneton	μB=eℏ2me	9.274 009 15(23)×10−24J/T
Bohr radius	a0=ℏ2mee2ke	5.291 772 085 9(36)×10−11m
Boltzmann’s constant	kB=RNA	1.380649×10–23joule per kelvin(J⋅K–1)
Compton wavelength	λC=hmec	2.426 310 217 5(33)×10−12m
Coulomb constant	ke=14πε0	8.987 551 788...×109N⋅m2/C2(exact)
Deuteron mass	md	3.343 583 20(17)×10−27kg
Electron mass	me	9.109 382 15(45)×10−31kg
Electron volt	eV	1.602 176 487(40)×10−19J
Elementary charge	e	1.602176634×10−19C
Gas constant	R	8.314 472(15)J/mol⋅K
Gravitational constant	G	6.674 28(67)×10−11N⋅m2/kg2
Neutron mass	mn	1.674 927 211(84)×10−27kg
Nuclear magneton	μn=eℏ2mp	5.050 783 24(13)×10−27J/T
Permeability of free space	μ0	4π×10−7T⋅m/A(exact)
Permittivity of free space	ε0=1μ0c2	8.854 187 817...×10−12C2/N⋅m2(exact)
Planck’s constant	h ℏ=h2π	6.62607015×10−34kg⋅m2⋅s–1
Proton mass	mp	1.672 621 637(83)×10−27kg
Rydberg constant	RH	1.097 373 156 852 7(73)×107m−1
Speed of light in vacuum	c	2.997 924 58×108m/s(exact)

TableC1 Fundamental Constants Note: These constants are the values recommended in 2006 by CODATA, based on a least-squares adjustment of data from different measurements. The numbers in parentheses for the values represent the uncertainties of the last two digits.

Useful combinations of constants for calculations:

hc=12,400eV⋅Å=1240eV⋅nm=1240MeV⋅fm

ℏc=1973eV⋅Å=197.3eV⋅nm=197.3MeV⋅fm

kee2=14.40eV⋅Å=1.440eV⋅nm=1.440MeV⋅fm

kBT=0.02585eV atT=300K