We explain what protons are, how they were discovered, their properties and characteristics. Also, what are nucleons.

Protons are found in the nucleus of atoms.

What is a proton?

The proton is a type ofsubatomic particle, that is, one of the minimum particles that make up the atom. It belongs to the fermion family and is endowed withelectric charge positive.

All thematter is made ofatoms, and these in turn, are essentially composed of three types of particles endowed with different electrical charge: electrons (negative charge), theneutrons (neutral charge) and protons (positive charge).

For a long time it was thought that the proton was a fundamental type of particle, that is, it could not be divided. However, today there is strong evidence that it is composed of quarks.

In any case, the proton is a stable subatomic particle. Unlike the electron, which orbits the nucleus of the atom, protons are contained in the atomic nucleus along with neutrons, contributing most of the atomic mass.

Discovery of the proton

Ernest Rutherford discovered the proton by experimenting with nitrogen.

Protons were discovered in 1918 by Ernest Rutherford (1871-1937), a British chemist and physicist. In the midst of experiments with gas of nitrogen, Rutherford noted that his instruments detected the presence of hydrogen nuclei by firing alpha particles at the gas.

He concluded that these nuclei must be fundamental particles of matter, without knowing at that time that, precisely, the nucleus of the hydrogen atom contains a single particle: a proton. Thus, it was decided to provide hydrogen with the atomic number 1.

However, it is known from previous scientific experiences that led to this discovery. For example, the German physicist Eugene Goldstein (1850-1930) in 1886 found positive ions inside the atom, through experiments with cathode rays.

In addition, the British J. J. Thompson (1856-1940) had already discovered electrons and their negative charge, that is, it was necessary that there be some other type of particle with opposite charge in the atom.

Properties and characteristics of the proton

Each proton is made up of two "up" quarks and one "down" quark.

Protons are stable composite particles, much more massive than an electron (1836 times) and endowed with a positive elemental charge of 1 (1.6 x 10-19 C). They are composed of three elementary particles or quarks: two "up"(Above) and one"down" (below). Their half-life is greater than 1035 years, from which point they are susceptible to decomposition.

Protons have, like other subatomic particles, their own spin, that is, an intrinsic and invariable angular momentum, which in this case is ½. This property is particularly useful for nuclear magnetic resonance and other modern technological applications.


Since they are normally found in the atomic nucleus, protons and neutrons are known as "nucleons." The electrons, on the other hand, orbit around them in a more or less scattered way.

Nucleons are bound together by strong nuclear forces, which only in particularly large atoms (such as Uranium) can yield to other forces, such as electromagnetic.

Nucleons make up the largest percentage of the mass of any atom and therefore determine the difference between a chemical element and the other: for example, the hydrogen atom has only one proton in its nucleus, while the helium atom has two protons and one or two neutrons, depending on the specific isotope.

Atomic number

In the periodic table the atomic number of each element can be observed.

The atomic number (Z) indicates how many protons a type of atom has in its nucleus. Each chemical element has a different atomic number, although its chemical behavior is rather determined by the number of electrons thatorbit around its nucleus (which for a neutral atom is equal to the number of protons).

Thus, for example, chlorine (Cl) has 17 protons in its nucleus, so that its atomic number is 17. This number never varies, not even between isotopes (versions) of the same atom, since they differ between yes only by the number of neutrons in its nucleus.

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