- Negatively charged atomic particle of small mass. Normal atoms consist of a positively-charged nucleus of protons and neutrons and an electrically balancing cloud of electrons in orbit around it.
- noun a sub-atomic particle that has a negative electrical charge
- A negatively charged stable subatomic particle. Electrons may be present as a constituent of an atom, or in a free state. When in the orbitals surrounding the nuclei of atoms, they determine many of its properties, such as chemical bonding. Each chemical element has a unique number of electrons, which is equal to the number of protons in its nucleus. Any inequality of this number results in an ion. As electrons flow through a conductor, an electric current is produced. The charge of an electron is equal to approximately 1.6022 × 10-19 coulomb, and its mass is approximately equal to 9.1094 × 10-31 kg. The positron is the anti-particle equivalent of the electron.