atom
  • The smallest particle that retains all the properties of an element. Atoms are composed of protons, neutrons, and electrons, with protium, which is hydrogen-1, being the sole exception as it has no neutrons. The positively charged proton and neutral neutron are clustered together in the nucleus. The negatively charged electrons revolve in energy levels surrounding the nucleus. Atoms are overall neutral in charge, as the number of electrons equals the number of protons. If the number of electrons is not equal to the number of protons, you have a charged atom, which is a type of ion.
  • In computers, the smallest element within an information structure. For example, a character or a pixel.

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