# Definition:Electron

## Electron

An electron is an elementary particle which contains a single unit of negative elementary electric charge.

### Charge

The electric charge on the electron is $-1.60217 \, 6634 \times 10^{−19}$ coulombs.

That is, a negative charge whose magnitude is the value of the elementary charge.

### Mass

The mass of the electron is given as:

 $\ds m_\E$ $\approx$ $\ds 9 \cdotp 10938 \, 37015 \, (28) \times 10^{-31}$ kilograms $\quad$ This sequence is A081801 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008). $\ds$ $\approx$ $\ds 9 \cdotp 10938 \, 37015 \, (28) \times 10^{-28}$ grams $\quad$ This sequence is A081801 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008). $\ds$ $\approx$ $\ds 5 \cdotp 48579 \, 90906 \, 5(16) \times 10^{-4}$ daltons $\quad$ This sequence is A003672 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).

The actual size of the electron is still unknown.

The current best estimate is that its radius has an upper limit of the order of $10^{-22}$ metres.

## Also see

• Results about electrons can be found here.

## Historical Note

The electron was discovered by Joseph John Thomson, who measured the Electron Charge to Mass Ratio in $1897$.

This happened as a result of several decades of work by many scientists.

## Linguistic Note

The adjectival form of the word electron is electronic.

Hence the word electronics as a collective term for devices exploiting the behaviour of electrons