Electron
Definition and meaning of Electron in chemistry.
Electron is a stable subatomic particle carrying one unit of negative electric charge that occupies the space surrounding an atom's nucleus, arranged in regions of probability called orbitals.
In more detail
Electrons are held near the nucleus by electrostatic attraction to protons, and their arrangement into shells and subshells (governed by the Aufbau principle, Pauli exclusion principle, and Hund's rule) explains the structure of the periodic table. Chemical bonding and reactivity depend almost entirely on valence electrons, the electrons in an atom's outermost shell, which atoms transfer or share to form ionic and covalent bonds. Although an electron has only about 1/1836 the mass of a proton, its behavior governs virtually all of chemistry, from bonding to conductivity to spectroscopy.
Key facts
| Symbol | e⁻ |
|---|---|
| Charge | -1 elementary charge (-1.602 × 10⁻¹⁹ C) |
| Relative mass | ~1/1836 of a proton (9.109 × 10⁻³¹ kg) |
| Field | General Chemistry |
A sodium atom has 11 electrons, with a single valence electron in its 3s orbital; sodium readily loses this electron to chlorine, forming Na+ and Cl- ions that combine as the ionic compound NaCl.
Frequently asked questions
Who discovered the electron?
J. J. Thomson discovered the electron in 1897 using cathode-ray tube experiments, showing it was a negatively charged particle far lighter than any known atom.
What is a valence electron?
A valence electron is an electron in an atom's outermost occupied shell; these electrons are the ones involved in forming chemical bonds and determine an element's chemical reactivity.