Discovery and History of Electrons
– Ancient Greeks observed the effect of electric force with amber and fur.
– William Gilbert coined the term ‘electrica’ for substances with similar properties to amber.
– Charles François du Fay discovered two kinds of charges – vitreous fluid and resinous fluid.
– Benjamin Franklin proposed that electricity consists of a single electrical fluid with positive and negative charges.
– Julius Plücker observed radiation emitted from the cathode, later identified as electrons.
– Richard Laming hypothesized the concept of an indivisible quantity of electric charge.
– George Johnstone Stoney named the charge ‘electron’ in 1891.
– J. J. Thomson and his team identified the electron as a particle in 1897.
– Electrons participate in nuclear reactions and can be created through beta decay.
– The antiparticle of the electron is called the positron.
Properties and Applications of Electrons
– Electrons play a crucial role in physical phenomena such as electricity, magnetism, chemistry, and thermal conductivity.
– Electrons exhibit properties of both particles and waves.
– Electrons have an intrinsic angular momentum (spin) and follow the Pauli exclusion principle.
– Electrons generate electric and magnetic fields and can absorb or radiate energy in the form of photons.
– Electrons are involved in various applications, including electronics, welding, radiation therapy, and particle accelerators.
Measurement and Structure of Electrons
– Cathode rays were discovered by Goldstein and further studied by Crookes.
– J. J. Thomson and his colleagues performed experiments indicating cathode rays were unique particles, which he called corpuscles.
– Millikan and Fletcher conducted the oil-drop experiment to measure the electron’s charge.
– Rutherford, Moseley, Franck, and Hertz established the structure of an atom with a dense nucleus and electrons.
– Bohr proposed that electrons resided in quantized energy states and explained hydrogen’s spectral lines.
Quantum Mechanics and Electron Structure
– Langmuir proposed that electrons were distributed in concentric shells of equal thickness.
– Pauli introduced the Pauli exclusion principle.
– Goudsmit and Uhlenbeck suggested that electrons possess intrinsic angular momentum and magnetic dipole moment.
– Louis de Broglie hypothesized that all matter can be represented as a de Broglie wave.
– The behavior of an electron in an atom is described by an orbital, which is a probability distribution.
Characteristics and Fundamental Properties of Electrons
– Electrons belong to the group of subatomic particles called leptons.
– Electrons have the lowest mass of any charged lepton and belong to the first generation of fundamental particles.
– The electron has an intrinsic angular momentum or spin of 1/2.
– The invariant mass of an electron is approximately 9.109×10^-31 kilograms.
– Electrons have an electric charge of -1.602176634×10^-19 coulombs. Source: https://en.wikipedia.org/wiki/Electron
The electron (
e−
or
β−
) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, per the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
 Hydrogen atomic orbitals at different energy levels. The more opaque areas are where one is most likely to find an electron at any given time. | |
| Composition | elementary particle |
|---|---|
| Statistics | fermionic |
| Family | lepton |
| Generation | first |
| Interactions | weak, electromagnetic, gravity |
| Symbol | e− , β− |
| Antiparticle | positron |
| Theorized | Richard Laming (1838–1851), G. Johnstone Stoney (1874) and others. |
| Discovered | J. J. Thomson (1897) |
| Mass | 9.1093837015(28)×10−31 kg 5.48579909065(16)×10−4 Da [1822.888486209(53)]−1 Da 0.51099895000(15) MeV/c2 |
| Mean lifetime | > 6.6×1028 years (stable) |
| Electric charge | −1 e −1.602176634×10−19 C |
| Magnetic moment | −9.2847647043(28)×10−24 J⋅T−1 −1.00115965218128(18) µB |
| Spin | 1 /2 ħ |
| Weak isospin | LH: − 1 /2, RH: 0 |
| Weak hypercharge | LH: −1, RH: −2 |
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry, and thermal conductivity; they also participate in gravitational, electromagnetic, and weak interactions. Since an electron has charge, it has a surrounding electric field; if that electron is moving relative to an observer, the observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated.
Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications, such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode-ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors, and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding.
In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode-ray tube experiment.
Electrons participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance, when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron, except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
