Page 609 - SUBSEC October 2017_Neat

SUMMARY OF KEY QUANTITIES, SYMBOLS AND UNITS (cont’d)

Quantity Usual Symbols Usual Unit

Other Quantities (cont’d)

-1
Avogadro constant NA mol

number density N m
-3
(number per unit volume)

Planck constant h J s

work function energy Φ J

activity of radioactive source A Bq

-1
decay constant λ s

half-life t½ s

relative atomic mass Ar

relative molecular mass Mr

atomic mass ma kg, u

electron mass me kg, u

neutron mass mn kg, u

proton mass mp kg, u

molar mass M kg

proton number Z

nucleon number A

neutron number N

-4
-2
Stefan-Boltzmann constant σ W m K

CXC A16/U2/17 109