Question

In atomic mass units, what is the mass of an electron?

Answer 1

Mass of an electron in atomic mass units :

• One unified atomic mass unit(amu) is defined as being equal to 1/ 12 th of the mass of a carbon-12 atom.
• We know, that the mass of an electron is given as; ${\mathrm{M}}_{\mathrm{electron}}=9.10938356\times {10}^{-31}\mathrm{kg}$
• Also, we have, have $1\mathrm{amu}=1.660538922\times {10}^{-27}\mathrm{kg}$
• Hence, the mass of an electron expressed in unified atomic mass units will be calculated as;

$$\begin{gathered} 9.10938356\times {10}^{-31}\mathrm{kg}\times \frac{1\mathrm{amu}}{1.660538922\times {10}^{-27}\mathrm{kg}} \\ =5.4858\times {10}^{-4}\mathrm{amu}. \end{gathered}$$

Hence, the mass of an electron in atomic mass units is $5.4858\times {10}^{-4}\mathrm{amu}$.