An electron is a fundamental subatomic particle. Electrons are not found within the dense core of an atom; instead, they exist in a cloud-like region surrounding the nucleus. This outer location means electrons are the particles that interact when atoms come close to one another and dictate how an element behaves in chemical reactions.
The Definitive Charge of an Electron
The electric charge of an electron is designated as negative. This charge is a fundamental property of the particle and is equal in magnitude to the charge of a proton. The convention of calling this charge “negative” is arbitrary and dates back to the 18th-century work of Benjamin Franklin, who assigned the labels “positive” and “negative” while studying static electricity. If Franklin had chosen the opposite labels, the electron would be called “positive” today, but its physical behavior would remain the same.
How Electron Charge Balances the Atom
The electron’s negative charge plays a direct role in maintaining the overall electrical neutrality of an atom. The atomic nucleus contains two other types of subatomic particles: protons, which carry an equivalent positive charge, and neutrons, which carry no charge. Since opposite charges attract, the negative electrons are bound to the atom by the electromagnetic force exerted by the positive protons in the nucleus.
For an atom to be electrically neutral, the total negative charge from all electrons must perfectly cancel out the total positive charge from all protons. This means that a neutral atom must contain an identical number of electrons and protons. For example, a carbon atom, which has six protons in its nucleus, must also have six electrons orbiting that nucleus to achieve a zero net charge.
The number of protons within the nucleus is known as the atomic number, which is the defining characteristic of an element. In a neutral atom, the number of electrons must equal the atomic number. If an atom gains or loses electrons, it develops a net electrical charge and is no longer neutral, becoming an ion.
The Role of Negative Charge in Chemistry and Current
The negative charge of the electron is the driving force behind both chemical reactions and electrical phenomena. In chemistry, the electrons in the outermost shell, known as valence electrons, are responsible for forming bonds between atoms. Atoms strive to achieve a stable arrangement of these valence electrons, often by interacting with other atoms.
The electron’s negative charge facilitates these interactions by being attracted to the positive nuclei of surrounding atoms. Chemical bonds form either when the negative electron is completely transferred from one atom to another, creating oppositely charged ions, or when electrons are shared between atoms. Sharing allows the negative charge to be simultaneously attracted to the positive nuclei of both atoms.
On a larger scale, the movement of electrons constitutes an electric current. In conductive materials, electrons are not tightly bound and can move freely from atom to atom, creating a collective, directed flow of negatively charged particles. The negative charge allows the electron to be repelled by a negative terminal and attracted to a positive terminal, enabling controlled movement in electronic circuits.