atomic number

atomic number
the number of positive charges or protons in the nucleus of an atom of a given element, and therefore also the number of electrons normally surrounding the nucleus. Abbr.: at. no.; Symbol: Z Also called proton number.
[1815-25]

* * *

Number of a chemical element in the systematic, ordered sequence shown in the periodic table.

The elements are arranged in order of increasing number of protons in the nucleus of the atom (the same as the number of electrons in the neutral atom), and that number for each element is its atomic number.

* * *

      the number of a chemical element (q.v.) in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number. An atom of iron has 26 protons in its nucleus; therefore the atomic number of iron is 26.

      In the symbol representing a particular nuclear or atomic species, the atomic number may be indicated as a left subscript. An atom or a nucleus of iron (chemical symbol Fe), for example, may be written 26Fe.

* * *


Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • atomic number — atomic num·ber nəm bər n an experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines… …   Medical dictionary

  • atomic number — n. Chem. a number representing the relative position of an element in the periodic table, in which the elements are arranged in the order of their nuclear charges; a number representing the positive charge or the number of protons in the nucleus… …   English World dictionary

  • atomic number — ► NOUN ▪ the number of protons in the nucleus of a chemical element s atom, which determines its place in the periodic table …   English terms dictionary

  • Atomic number — См. Атомный номер Термины атомной энергетики. Концерн Росэнергоатом, 2010 …   Термины атомной энергетики

  • Atomic number — See also: List of elements by atomic number An explanation of the superscripts and subscripts seen in atomic number notation. In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the… …   Wikipedia

  • atomic number — UK / US noun [countable] Word forms atomic number : singular atomic number plural atomic numbers chemistry the number of protons in the nucleus of an atom …   English dictionary

  • atomic number — noun the order of an element in Mendeleyev s table of the elements; equal to the number of protons in the nucleus or electrons in the neutral state of an atom of an element • Hypernyms: ↑number • Hyponyms: ↑magic number * * * aˌtomic ˈnumber f13… …   Useful english dictionary

  • atomic number —    The atomic number was originally defined (about 1865) simply as an index describing the position of an element in the periodic table. Not until 1913 was it known that the atomic number is actually a unit of measurement, equal to the number of… …   Dictionary of units of measurement

  • atomic number — atominis skaičius statusas T sritis Standartizacija ir metrologija apibrėžtis Cheminio elemento eilės numeris periodinėje elementų sistemoje. Apibūdina atomo branduolio protonų skaičių, taip pat atitinkamo neutraliojo atomo elektronų skaičių.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • atomic number — atominis skaičius statusas T sritis Standartizacija ir metrologija apibrėžtis Protonų skaičius atomo branduolyje. atitikmenys: angl. atomic number; charge number; ordinal number; proton number vok. Atomnummer, f; Atomzahl, f; Kernladungszahl, f;… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”