An electron is a fundamental particle that carries a negative charge. Although the charge it carries is equal and opposite to that of another important particle, the proton, it has only 0.05% of a proton's mass. Calculating the speed (or velocity) of an electron is important for solving many different physics and chemistry problems. The calculation and units may seem daunting to work with at first, but once simplified can be done with ease.

Determine the mass of a single electron, which is a constant value, and can be found in any good physics resource. The mass of one electron is 9.0 x 10^-31 kg.

Assume that your electron is starting at rest, therefore its energy (E) is equal to (1/2)mv^2.

Find the energy of your electron in joules. In this example, assume E=1 joule.

Write out the calculation and substitute your values: 1 joule = (1/2) * (9.0 x 10^-31 kg) * v^2.

Follow through with your calculation to find that your electron is moving at 9.5 x 10^-16 m/s.