Electrons

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. 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.