Nuclear Power Plant Isar, Germany

Spent nuclear fuel pool

Turbine of a nuclear plant



An electron is a stable negatively charged elementary particle which is one of the fundamental components of the atom. For this reason it can also be defined as a subatomic particle. It is part of the group of leptons.

Electrons may appear in the free state (without being attached to any atom) or attached to the nucleus of an atom. There are electrons in atoms spherical layers of different radious. These spherical layers represent energy levels. The larger spherical shell, the greater the energy contained in the electron.

In the electrical conductors, the current flows results from the electrons of atoms circulating individually from one atom to another in the direction of the negative pole to the positive pole of the electrical conductor. In semiconducting materials, the electric current also occurs by the movement of electrons.

In some cases,  it is more illustrative to envision the current as a movement of electric current are the gaps of electrons from atom to atom. An electron deficient atom in a semiconductor is called hole. The holes generally "move" between electrical poles from positive to negative.

Electrons are one of the components of the atom

History and discovery of the electron

The electron was the first elementary particle discovered. By the late nineteenth century devoted significant time to investigate electrical discharges in rarefied gases effort.

1895 Jean Perrin In analyzing the electrical charge of so-called cathode ray (cathode) showed transporting negative charge. Soon, J.J. Thomson performed classic experiment in which he managed to determine the specific charge of the particles. According to Thomson, the charges constituted cathode rays and electrons called. Millikan used the relation between charge / mass (e / m) obtained by Thomson for a new relationship. Millikan's experiment became famous and was able to measure in 1909 the electron charge and mass m.

The discovery of the electron began a new stage of physics. Could corroborate the hypothesis that the electron is an elementary particle of the universe from which all atoms are formed.
It has been found that the electron mass increases with speed, according to the predictions of relativistic mechanics of Albert Einsein. It also verified the wave nature of the electron.

The production of free electrons by different methods and their behavior in various media have found an extraordinary practical application and have developed a new branch of physics and electricity, electronics.

Physical Properties of electrons

The charge of a single electron is considered as the unit of electric charge. Negative polarity is assigned, so we say that the electron has a negative charge. The charge of an electron is equal, but opposite direction to the positive charge of a proton or a hole.

The amount of electric charge is not measured in terms of the charge of an electron because is extremely small. Instead, the Coulomb used with symbol C. The Coulomb is the standard unit of quantity of electric charge. A Coulomb represents about 6.24 x 1018 electrons.

The electric charge of an electron is 1.60 x 10-19 C and the electron mass is about 9.11 x 10-31 kg.

Electrons move to an appreciable fraction of the speed of light, for example, a particle accelerator, has a greater mass because of relativistic effects.


Published: October 27, 2016
Last review: October 27, 2016