Difference between revisions of "Atomic number"
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The '''atomic number''' (symbol: '''''Z''''') of a [[chemical element]] is the number of [[proton]]s in the [[Atomic nucleus|nucleus]] of each atom of that element.<ref>{{GoldBookRef|title=atomic number|file=A00499|accessdate=2010-03-20}}.</ref> It is also sometimes called the '''proton number''' of a given [[nuclide]]. The atomic number is equal to the positive [[charge]] on the nucleus and, for a neutral atom, to the number of electrons in the atom. | The '''atomic number''' (symbol: '''''Z''''') of a [[chemical element]] is the number of [[proton]]s in the [[Atomic nucleus|nucleus]] of each atom of that element.<ref>{{GoldBookRef|title=atomic number|file=A00499|accessdate=2010-03-20}}.</ref> It is also sometimes called the '''proton number''' of a given [[nuclide]]. The atomic number is equal to the positive [[charge]] on the nucleus and, for a neutral atom, to the number of electrons in the atom. | ||
| − | An element's atomic number determines its place in the [[periodic table]], and the discovery of atomic number in 1913 (by [[Henry Moseley]])<ref>{{citation | last = Moseley | first = H. G. J. | authorlink = Henry Moseley | The High Frequency Spectra of the Elements | journal = | + | An element's atomic number determines its place in the [[periodic table]], and the discovery of atomic number in 1913 (by [[Henry Moseley]])<ref>{{citation | last = Moseley | first = H. G. J. | authorlink = Henry Moseley | title = The High Frequency Spectra of the Elements | journal = Philos. Mag. | year = 1913 | page = 1024 | url = http://www.chemistry.co.nz/henry_moseley_article.htm}}. {{citation | last = Moseley | first = H. G. J. | authorlink = Henry Moseley | title = The High Frequency Spectra of the Elements. Part II | journal = Philos. Mag. | year = 1914 | page = 703–13 | url = http://web.mit.edu/8.13/www/pdf_files/moseley-1913-high-freq-spectra-elements-part2.pdf}}.</ref> resolved several inconsistencies in the ordering of the periodic table by [[atomic weight]]. The relationship between atomic number and the [[periodicity]] of chemical properties was rationalized by [[Wolfgang Pauli]] in 1925. |
==References== | ==References== | ||
Latest revision as of 19:01, 17 April 2011
The atomic number (symbol: Z) of a chemical element is the number of protons in the nucleus of each atom of that element.[1] It is also sometimes called the proton number of a given nuclide. The atomic number is equal to the positive charge on the nucleus and, for a neutral atom, to the number of electrons in the atom.
An element's atomic number determines its place in the periodic table, and the discovery of atomic number in 1913 (by Henry Moseley)[2] resolved several inconsistencies in the ordering of the periodic table by atomic weight. The relationship between atomic number and the periodicity of chemical properties was rationalized by Wolfgang Pauli in 1925.
References
- ↑ atomic number, <http://goldbook.iupac.org/A00499.html> (accessed 20 March 2010), Compendium of Chemical Terminology Internet edition; International Union of Pure and Applied Chemistry (IUPAC).
- ↑ Moseley, H. G. J. The High Frequency Spectra of the Elements. Philos. Mag. 1913, 1024, <http://www.chemistry.co.nz/henry_moseley_article.htm>. Moseley, H. G. J. The High Frequency Spectra of the Elements. Part II. Philos. Mag. 1914, 703–13, <http://web.mit.edu/8.13/www/pdf_files/moseley-1913-high-freq-spectra-elements-part2.pdf>.
External links
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See also the corresponding article on Wikipedia. |
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