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What Is An Electron

What Is An Electron

Stylized Lithium Atom by Halfdan

What is an electron? Easily put, an electron is a subatomic particle that carries a negative electric charge. There are no known components, so it is believed to be an elementary particle(basic building block of the universe). The mass of an electron is 1/1836 of its proton. Electrons have an antiparticle called a positron. Positrons are identical to electrons except that all of its properties are the exact opposite. When electrons and positrons collide, they can be destroyed and will produce a pair (or more) of gamma ray photons. Electrons have gravitational, electromagnetic, and weak interactions.

In 1913, Niels Bohr postulated that electrons resided in quantized energy states, with the energy determined by the spin(angular momentum)of the electron’s orbits and that the electrons could move between these orbits by the emission or absorption of photons. These orbits explained the spectral lines of the hydrogen atom. The Bohr model failed to account for the relative intensities of the spectral lines and it was unsuccessful in explaining the spectra of more complex atom. Gilbert Lewis proposed in 1916 that a ‘covalent bond’ between two atoms is maintained by a pair of shared electrons. In 1919, Irving Langmuir improved on Lewis’ static model and suggested that all electrons were distributed in successive “concentric(nearly) spherical shells, all of equal thickness”. The shells were divided into a number of cells containing one pair of electrons. This model was able to qualitatively explain the chemical properties of all elements in the periodic table.

The invariant mass of an electron is 9.109×10-31 or 5.489×10-4 of the atomic mass unit. According to Einstein’s principle of mass-energy equivalence, this mass corresponds to a rest energy of .511MeV. Electrons have an electric charge of -1.602×10 coulomb. This a standard unit of charge for subatomic particles. The electron charge is identical to the charge of a proton. In addition to spin, the electron has an intrinsic magnetic moment along its spin axis. It is approximately equal to one Bohr magneton. The orientation of the spin with respect to the momentum of the electron defines the property of elementary particles known as helicity. Observing a single electron shows the upper limit of the particle’s radius is 10-22 meters. Some elementary particles decay into less massive particles. But an electron is thought to be stable on the grounds that it is the least massive particle with non-zero electric charge.

Understanding what is an electron is to begin to understand the basic building blocks of the universe. A very elementary understanding, but a building block to great scientific thought.

We have written many articles about the electron for Universe Today. Here’s an article about the Electron Cloud Model, and here’s an article about the charge of electron.

If you’d like more info on the Electron, check out the History of the Electron Page, and here’s a link to the article about Killer Electrons.

We’ve also recorded an entire episode of Astronomy Cast all about the Composition of the Atom. Listen here, Episode 164: Inside the Atom.

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