ancient Greeks noticed that
amber attracted small objects when rubbed with fur. Along with
lightning, this phenomenon is one of humanity's earliest recorded experiences with
 In his 1600 treatise
De Magnete, the English scientist
William Gilbert coined the
New Latin term electricus, to refer to this property of attracting small objects after being rubbed.
 Both electric and electricity are derived from the Latin ēlectrum (also the root of the
alloy of the same name), which came from the Greek word for amber, ἤλεκτρον (ēlektron).
In the early 1700s,
Francis Hauksbee and French chemist
Charles François du Fay independently discovered what they believed were two kinds of frictional electricity—one generated from rubbing glass, the other from rubbing resin. From this, du Fay theorized that electricity consists of two
electrical fluids, vitreous and resinous, that are separated by friction, and that neutralize each other when combined.
 American scientist
Ebenezer Kinnersley later also independently reached the same conclusion.
:118 A decade later
Benjamin Franklin proposed that electricity was not from different types of electrical fluid, but a single electrical fluid showing an excess (+) or deficit (-). He gave them the modern
charge nomenclature of positive and negative respectively.
 Franklin thought of the charge carrier as being positive, but he did not correctly identify which situation was a surplus of the charge carrier, and which situation was a deficit.
Between 1838 and 1851, British natural philosopher
Richard Laming developed the idea that an atom is composed of a core of matter surrounded by subatomic particles that had unit
 Beginning in 1846, German physicist
William Weber theorized that electricity was composed of positively and negatively charged fluids, and their interaction was governed by the
inverse square law. After studying the phenomenon of
electrolysis in 1874, Irish physicist
George Johnstone Stoney suggested that there existed a "single definite quantity of electricity", the charge of a
ion. He was able to estimate the value of this elementary charge e by means of
Faraday's laws of electrolysis.
 However, Stoney believed these charges were permanently attached to atoms and could not be removed. In 1881, German physicist
Hermann von Helmholtz argued that both positive and negative charges were divided into elementary parts, each of which "behaves like atoms of electricity".
Stoney initially coined the term electrolion in 1881. Ten years later, he switched to electron to describe these elementary charges, writing in 1894: "... an estimate was made of the actual amount of this most remarkable fundamental unit of electricity, for which I have since ventured to suggest the name electron". A 1906 proposal to change to electrion failed because
Hendrik Lorentz preferred to keep electron.
 The word electron is a combination of the words electric and ion.
 The suffix
-on which is now used to designate other subatomic particles, such as a proton or neutron, is in turn derived from electron.
A beam of electrons deflected in a circle by a magnetic field
The German physicist
Johann Wilhelm Hittorf studied electrical conductivity in
rarefied gases: in 1869, he discovered a glow emitted from the
cathode that increased in size with decrease in gas pressure. In 1876, the German physicist
Eugen Goldstein showed that the rays from this glow cast a shadow, and he dubbed the rays
 During the 1870s, the English chemist and physicist Sir
William Crookes developed the first cathode ray tube to have a
high vacuum inside.
 He then showed that the luminescence rays appearing within the tube carried energy and moved from the cathode to the
anode. Furthermore, by applying a magnetic field, he was able to deflect the rays, thereby demonstrating that the beam behaved as though it were negatively charged.
 In 1879, he proposed that these properties could be explained by what he termed 'radiant matter'. He suggested that this was a fourth state of matter, consisting of negatively charged
molecules that were being projected with high velocity from the cathode.
The German-born British physicist
Arthur Schuster expanded upon Crookes' experiments by placing metal plates parallel to the cathode rays and applying an
electric potential between the plates. The field deflected the rays toward the positively charged plate, providing further evidence that the rays carried negative charge. By measuring the amount of deflection for a given level of
current, in 1890 Schuster was able to estimate the
charge-to-mass ratio of the ray components. However, this produced a value that was more than a thousand times greater than what was expected, so little credence was given to his calculations at the time.
Hendrik Lorentz suggested that the mass of these particles (electrons) could be a consequence of their electric charge.
In 1896, the British physicist
J. J. Thomson, with his colleagues
John S. Townsend and
H. A. Wilson,
 performed experiments indicating that cathode rays really were unique particles, rather than waves, atoms or molecules as was believed earlier.
 Thomson made good estimates of both the charge e and the mass m, finding that cathode ray particles, which he called "corpuscles," had perhaps one thousandth of the mass of the least massive ion known: hydrogen.
 He showed that their charge-to-mass ratio, e/m, was independent of cathode material. He further showed that the negatively charged particles produced by radioactive materials, by heated materials and by illuminated materials were universal.
 The name electron was again proposed for these particles by the Irish physicist
George Johnstone Stoney, and the name has since gained universal acceptance.
While studying naturally
fluorescing minerals in 1896, the French physicist
Henri Becquerel discovered that they emitted radiation without any exposure to an external energy source. These
radioactive materials became the subject of much interest by scientists, including the New Zealand physicist
Ernest Rutherford who discovered they emitted particles. He designated these particles
beta, on the basis of their ability to penetrate matter.
 In 1900, Becquerel showed that the beta rays emitted by
radium could be deflected by an electric field, and that their mass-to-charge ratio was the same as for cathode rays.
 This evidence strengthened the view that electrons existed as components of atoms.
The electron's charge was more carefully measured by the American physicists
Robert Millikan and
Harvey Fletcher in their
oil-drop experiment of 1909, the results of which were published in 1911. This experiment used an electric field to prevent a charged droplet of oil from falling as a result of gravity. This device could measure the electric charge from as few as 1–150 ions with an error margin of less than 0.3%. Comparable experiments had been done earlier by Thomson's team,
 using clouds of charged water droplets generated by electrolysis,
 and in 1911 by
Abram Ioffe, who independently obtained the same result as Millikan using charged microparticles of metals, then published his results in 1913.
 However, oil drops were more stable than water drops because of their slower evaporation rate, and thus more suited to precise experimentation over longer periods of time.
Around the beginning of the twentieth century, it was found that under certain conditions a fast-moving charged particle caused a condensation of
supersaturated water vapor along its path. In 1911,
Charles Wilson used this principle to devise his
cloud chamber so he could photograph the tracks of charged particles, such as fast-moving electrons.
Bohr model of the atom
, showing states of electron with energy
by the number n. An electron dropping to a lower orbit emits a photon equal to the energy difference between the orbits.
By 1914, experiments by physicists
James Franck and
Gustav Hertz had largely established the structure of an atom as a dense
nucleus of positive charge surrounded by lower-mass electrons.
 In 1913, Danish physicist
Niels Bohr postulated that electrons resided in quantized energy states, with their energies determined by the angular momentum of the electron's orbit about the nucleus. The electrons could move between those states, or orbits, by the emission or absorption of photons of specific frequencies. By means of these quantized orbits, he accurately explained the
spectral lines of the hydrogen atom.
 However, Bohr's model failed to account for the relative intensities of the spectral lines and it was unsuccessful in explaining the spectra of more complex atoms.
Chemical bonds between atoms were explained by
Gilbert Newton Lewis, who in 1916 proposed that a
covalent bond between two atoms is maintained by a pair of electrons shared between them.
 Later, in 1927,
Walter Heitler and
Fritz London gave the full explanation of the electron-pair formation and chemical bonding in terms of
 In 1919, the American chemist
Irving Langmuir elaborated on the Lewis' static model of the atom and suggested that all electrons were distributed in successive "concentric (nearly) spherical shells, all of equal thickness".
 In turn, he divided the shells into a number of cells each of which contained one pair of electrons. With this model Langmuir was able to qualitatively explain the
chemical properties of all elements in the periodic table,
 which were known to largely repeat themselves according to the
In 1924, Austrian physicist
Wolfgang Pauli observed that the shell-like structure of the atom could be explained by a set of four parameters that defined every quantum energy state, as long as each state was occupied by no more than a single electron. This prohibition against more than one electron occupying the same quantum energy state became known as the
Pauli exclusion principle.
 The physical mechanism to explain the fourth parameter, which had two distinct possible values, was provided by the Dutch physicists
Samuel Goudsmit and
George Uhlenbeck. In 1925, they suggested that an electron, in addition to the angular momentum of its orbit, possesses an intrinsic angular momentum and
magnetic dipole moment.
 This is analogous to the rotation of the Earth on its axis as it orbits the Sun. The intrinsic angular momentum became known as
spin, and explained the previously mysterious splitting of spectral lines observed with a high-resolution
spectrograph; this phenomenon is known as
fine structure splitting.
In his 1924 dissertation Recherches sur la théorie des quanta (Research on Quantum Theory), French physicist
Louis de Broglie hypothesized that all matter can be represented as a
de Broglie wave in the manner of
 That is, under the appropriate conditions, electrons and other matter would show properties of either particles or waves. The
corpuscular properties of a particle are demonstrated when it is shown to have a localized position in space along its trajectory at any given moment.
 The wave-like nature of light is displayed, for example, when a beam of light is passed through parallel slits thereby creating
interference patterns. In 1927
George Paget Thomson, discovered the interference effect was produced when a beam of electrons was passed through thin metal foils and by American physicists
Clinton Davisson and
Lester Germer by the reflection of electrons from a crystal of
In quantum mechanics, the behavior of an electron in an atom is described by an
, which is a probability distribution rather than an orbit. In the figure, the shading indicates the relative probability to "find" the electron, having the energy corresponding to the given
, at that point.
De Broglie's prediction of a wave nature for electrons led
Erwin Schrödinger to postulate a wave equation for electrons moving under the influence of the nucleus in the atom. In 1926, this equation, the
Schrödinger equation, successfully described how electron waves propagated.
 Rather than yielding a solution that determined the location of an electron over time, this wave equation also could be used to predict the probability of finding an electron near a position, especially a position near where the electron was bound in space, for which the electron wave equations did not change in time. This approach led to a second formulation of
quantum mechanics (the first by Heisenberg in 1925), and solutions of Schrödinger's equation, like Heisenberg's, provided derivations of the energy states of an electron in a hydrogen atom that were equivalent to those that had been derived first by Bohr in 1913, and that were known to reproduce the hydrogen spectrum.
 Once spin and the interaction between multiple electrons were describable, quantum mechanics made it possible to predict the configuration of electrons in atoms with atomic numbers greater than hydrogen.
In 1928, building on Wolfgang Pauli's work,
Paul Dirac produced a model of the electron – the
Dirac equation, consistent with
relativity theory, by applying relativistic and symmetry considerations to the
hamiltonian formulation of the quantum mechanics of the electro-magnetic field.
 In order to resolve some problems within his relativistic equation, Dirac developed in 1930 a model of the vacuum as an infinite sea of particles with negative energy, later dubbed the
Dirac sea. This led him to predict the existence of a positron, the
antimatter counterpart of the electron.
 This particle was discovered in 1932 by
Carl Anderson, who proposed calling standard electrons negatrons, and using electron as a generic term to describe both the positively and negatively charged variants.
Willis Lamb, working in collaboration with graduate student
Robert Retherford, found that certain quantum states of the hydrogen atom, which should have the same energy, were shifted in relation to each other, the difference came to be called the
Lamb shift. About the same time,
Polykarp Kusch, working with
Henry M. Foley, discovered the magnetic moment of the electron is slightly larger than predicted by Dirac's theory. This small difference was later called
anomalous magnetic dipole moment of the electron. This difference was later explained by the theory of
quantum electrodynamics, developed by
Julian Schwinger and
Richard Feynman in the late 1940s.
With the development of the
particle accelerator during the first half of the twentieth century, physicists began to delve deeper into the properties of
 The first successful attempt to accelerate electrons using
electromagnetic induction was made in 1942 by
Donald Kerst. His initial
betatron reached energies of 2.3 MeV, while subsequent betatrons achieved 300 MeV. In 1947,
synchrotron radiation was discovered with a 70 MeV electron synchrotron at
General Electric. This radiation was caused by the acceleration of electrons through a magnetic field as they moved near the speed of light.
With a beam energy of 1.5 GeV, the first high-energy particle
ADONE, which began operations in 1968.
 This device accelerated electrons and positrons in opposite directions, effectively doubling the energy of their collision when compared to striking a static target with an electron.
Large Electron–Positron Collider (LEP) at
CERN, which was operational from 1989 to 2000, achieved collision energies of 209 GeV and made important measurements for the
Standard Model of particle physics.
Confinement of individual electrons
Individual electrons can now be easily confined in ultra small (L = 20 nm, W = 20 nm) CMOS transistors operated at cryogenic temperature over a range of −269 °C (4
K) to about −258 °C (15
 The electron wavefunction spreads in a semiconductor lattice and negligibly interacts with the valence band electrons, so it can be treated in the single particle formalism, by replacing its mass with the
effective mass tensor.