# The Electron

Submitted by jwmoore on Wed, 01/12/2011 - 01:28

$\frac{\text{96 500 C mol}^{-\text{1}}}{\text{1}\text{.76 }\times \text{ 10}^{\text{8}}\text{ C g}^{-\text{1}}}=\text{5}\text{.48 }\times \text{ 10}^{-\text{4}}\text{ g mol}^{-\text{1}}$
Thus the molar massThe mass of a mole of substance; the same as molecular weight for molecular substances. of an electron is 5.48 × 10–4 g mol–1, and if we think of the electron as an “atom“(or indivisible particle) of electricity, its atomic weightThe average mass of the naturally occurring isotopes of an element, taking into account the different natural abundances of the isotopes. Expressed relative to the value of exactly 12 for carbon-12; also called atomic mass. would be 0.000548—only $\tfrac{1}{1837}$ that of hydrogen, the lightest element known. In 1909 the American physicist Robert A. Millikan (1863 to 1953) was able to determine the charge on an electron independently of its mass. His value of 1.6 × 10–19 C can be combined with Thomson’s charge-to-mass ratio to give an independent check on the molar mass for the electron
$\frac{\text{1}\text{.60 }\times \text{ 10}^{-\text{19}}\text{ C}}{\text{1}\text{.76 }\times \text{ 10}^{\text{8}}\text{ C g}^{-\text{1}}}\text{ }\times \text{ 6}\text{.022 }\times \text{ 10}^{\text{23}}\text{ mol}^{-\text{1}}=\text{5}\text{.47 }\times \text{ 10}^{-\text{4}}\text{ g mol}^{-\text{1}}$