An electron is a fundamental subatomic particle that carries a single unit of negative electrical charge. Electrons are the source of all negative charge in an atom. This negative charge is conventionally assigned a relative value of negative one (–1). This property governs all chemical interactions.
Defining the Electron and its Negative Charge
The electron is an extremely small particle, residing in orbital paths that surround the atom’s central nucleus. Its mass is negligible, approximately 1/1836th the mass of a proton. The electron’s negative charge is a fixed, measurable quantity, specifically \(-1.602 \times 10^{-19}\) Coulombs. This value, known as the elementary charge, is a fundamental constant. The designation of this charge as “negative” is a historical convention used consistently in physics and chemistry. This uniform negative property makes electrons the primary driver of electricity and chemical bonding.
The Atomic Balancing Act: Protons and Neutrons
The negative charge of the electron is balanced within the atom by the presence of other subatomic particles. Deep within the dense nucleus are protons, which possess an electrical charge equal in magnitude but opposite in sign to the electron. Each proton carries a relative charge of positive one \((+1)\), neutralizing the charge of a single electron.
Neutrons are also housed in the nucleus; they have nearly the same mass as protons but carry no electrical charge. In an uncharged atom, the number of orbiting electrons is precisely equal to the number of protons in the nucleus. This equal count results in a net electrical charge of zero, creating a stable, neutral atom.
Protons and neutrons are significantly heavier than electrons, giving the nucleus almost all of the atom’s mass. The strong attraction between the positively charged nucleus and the negatively charged electron cloud holds the atomic structure together.
Electrons in Action: Creating Ions
The negative charge of the electron allows atoms to form chemical bonds by either gaining or losing these particles, thereby creating charged atoms called ions. When an atom loses one or more of its negatively charged electrons, it is left with an excess of positive protons in the nucleus. This results in an overall positive charge, and the resulting particle is called a cation.
Conversely, an atom can gain one or more electrons. This action introduces more negative charge than there are positive protons, giving the atom a net negative charge. This negatively charged particle is known as an anion.
Both cations and anions are atoms that have traded their electrical neutrality for an overall charge, a process called ionization. The movement of electrons, and the resulting formation of ions, is the basis of ionic bonding, where oppositely charged ions attract each other to form stable chemical compounds. The negative charge of the electron is the driving force behind this fundamental chemical reactivity. This ability to transfer negative charge is how the electron governs the formation of molecules and the chemistry of life.