Elementary charge

The elementary charge e is an indivisible quantity of charge. Hence it is the smallest charge existing in nature. The charge of an electron is −e, while the charge of a proton is +e. The elementary charge is one of the fundamental physical constants and has a value of 1.602 176 487 × 10⁻¹⁹ coulomb.

External link

http://physics.nist.gov/cgi-bin/cuu/Value?e