Nuclear Power Plant Isar, Germany

Spent nuclear fuel pool

Turbine of a nuclear plant

What Is the Atomic Number?

The atomic number is a physical and chemical concept related to the structure of the atoms of each element. The total number of protons (elementary positive charges) of the nucleus of a given atom is treated. It is represented by the letter Z. The conventional symbol Z possibly comes from the German word Z ahl which means number.

What is the atomic number?

The atomic number is used to classify elements within the periodic table of elements.

The sum of the atomic number Z and the number of neutrons N gives the mass number A of an atom. Atoms with the same atomic number Z, but different numbers of neutrons N, and therefore different atomic masses, are known as isotopes.

The search for new elements is usually done using atomic numbers. As of 2010, all elements with atomic numbers from 1 to 118 have been able to oservate. The synthesis of new elements is achieved by bombarding atoms of heavy elements with conions, so that the sum of the atomic numbers Of the elements and ionic is equal to the atomic number of the element that is being created. In general, the half-life becomes shorter as the atomic number increases.

Chemical Properties of Atomic Number

Each element has a specific set of chemical properties as a consequence of the number of electrons present in the neutral atom, which is Z (the atomic number). The configuration of these electrons is derived from the principles of quantum mechanics. The number of electrons in the electron reservoirs of each element, in particular the outermost valence layer, is the primary factor in determining its chemical bonding behavior. Therefore, it is the atomic number alone that determines the chemical properties of an element; And it is for this reason that an element can be defined as consistent in any mixture of atoms with a given atomic number.

Evolution of Atomic Number over the Course of History

At first, the atomic number was the order that was given to an element when ordered by increasing order according to their atomic masses.

In 1913, Johannes H. van den Broek, analyzing all known information, discovered that the number of elementary charges of the atomic nucleus was equal to the atomic number. Later, Niels Bohr adopted this discovery to develop his quantum theory on the structure of atoms and the origin of spectra.

Currently, Z is a known nuclear quantity with no error for all nuclei. However, the effective charge Ze is known with its corresponding experimental errors, like any physical magnitude.


Published: May 20, 2019
Last review: May 20, 2019