Electron

An electron is a subatomic particle with a negative charge.

Electrons are the negatively charged part of an atom, the exist outside the nucleus arranged into 'shells'. Removal or addition of electrons will alter the charge of an atom and form an ion. In terms of oxidation and reduction reaction, this also involve electron. Where oxidation is involving the loss of electron, while gaining electron will involve in reduction process. They are also the smallest part of the atom, carrying a atomic mass of roughly 0.005.

Electrons are used in Electron Microscopy, there are two kinds of EM; the Scanning Electron Microscope and the Transient Electron Microscope.