We explain what protons are, how they were discovered, their properties and characteristics. Also, what are nucleons.
What is a proton?
The proton It is a type of subatomic particle that is, one of the minimal particles that constitute the atom. It belongs to the fermion family and is endowed with a positive electrical charge.
All matter is made of atoms, and these, in turn, are essentially composed of three types of particles endowed with different electrical charges: electrons (negative charge), neutrons (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 providing most of the atomic mass.
See also: Atomic models
Discovery of the proton
The protons were discovered in 1918 by Ernest Rutherford (1871-1937), British chemist and physicist. In the midst of experiments with nitrogen gas, Rutherford noticed 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. It was so decided to give hydrogen 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.
Furthermore, the British JJ Thompson (1856-1940) had already discovered electrons and their negative charge, meaning that it was necessary for there to be some other type of particle with an opposite charge in the atom.
See also: Rutherford atomic model
Properties and characteristics of the proton
The protons are stable composite particles much more massive than an electron (1836 times) and endowed with a positive elementary 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). Its 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 invariant angular momentum, which in this case is ½. This property is particularly useful for nuclear magnetic resonance and other modern technological applications.
Nucleons
Since they are normally found in the atomic nucleus, Protons and neutrons are known as “nucleons.”. Electrons, on the other hand, orbit around them in a more or less dispersed manner.
The nucleons are linked together by strong nuclear forces which only in cases of particularly large atoms (such as Uranium) can yield to other forces, such as electromagnetic forces.
The nucleons make up the largest percentage of the mass of an atom any and determine, therefore, the difference between one 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 isotope. specific.
Atomic number
The atomic number (Z) indicates how many protons a type of atom has at its core. Each chemical element has a different atomic number, although its chemical behavior is rather determined by the number of electrons orbiting 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 its atomic number is 17. This number never varies, not even between isotopes (versions) of the same atom, since they differ between yes only because of the number of neutrons in its nucleus.
Continue with: Antimatter
References
- “Proton” on Wikipedia.
- “Atomic structure, atom, electron, proton, neutron, atomic number, mass, ion” (video) in Academia Internet.
- “The Proton” in Hyperphysics at Georgia State University (USA).
- “Neutrons and protons in atomic nuclei” in Nature.
- “Proton (subatomic particle)” in The Encyclopaedia Britannica.
