An electron is a fundamental subatomic particle that orbits the nucleus of every atom. It carries a fundamental negative electrical charge. This charge is the driving force behind virtually all chemical reactions and electrical phenomena observed in the universe. The electron’s charge is a fixed, indivisible quantity that dictates its interactions with other particles and forces.
The Polarity of the Electron
The designation of the electron’s charge as negative is a matter of historical convention rather than an inherent physical law. This system traces back to the 18th-century work of Benjamin Franklin, who arbitrarily assigned “positive” and “negative” signs during his experiments with static electricity. This convention established the polarity system where like charges repel and opposite charges attract. Because the charge discovered on the electron matched the sign Franklin had labeled “negative,” the electron was assigned a negative sign. The proton, found in the atom’s nucleus, carries a charge of the exact same magnitude but with the opposite, positive sign, ensuring atoms can achieve electrical neutrality.
Quantifying the Charge
The precise magnitude of the electron’s electrical charge is a fixed constant of nature used as the foundation for electrical measurements. This quantity is referred to as the elementary charge, symbolized by \(e\), and the electron’s charge is therefore written as \(-e\). In the International System of Units (SI), the standard unit for electrical charge is the Coulomb (C), and the electron’s charge is exactly \(-1.602176634 \times 10^{-19}\) Coulombs. To put this charge into perspective, it takes approximately \(6.24 \times 10^{18}\) electrons to accumulate a total charge of one Coulomb. The elementary charge is so fundamental that since the 2019 revision of the SI, it is one of the seven defining constants used to specify all other base units.
How This Charge Shapes Matter
The negative charge of the electron is the driving mechanism for the structure and behavior of all matter. In an electrically neutral atom, the total negative charge of its electrons precisely balances the total positive charge of its protons in the nucleus. This electrostatic attraction between opposite charges holds the entire atom together.
The ability of atoms to gain or lose electrons allows for the formation of ions. An atom that gains an electron acquires a net negative charge, while one that loses an electron acquires a net positive charge. This charge transfer and the resulting electrostatic attraction between positive and negative ions is the basis for ionic bonding, which forms compounds like table salt.
The negative charge is also central to covalent bonding, where atoms share electrons to achieve a stable configuration. The uneven sharing of these electrons can lead to polar molecules, which have slightly positive and negative ends. In the context of electricity, the movement of this negative charge through a conductor is defined as electric current.