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halogen
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A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. halogen lamp Diagram showing the formation of an ionic bond between sodium (Na) and chlorine (Cl) atoms. Sodium loses an electron to become Na+, chlorine gains an electron to become Cl-, resulting in sodium chloride (NaCl), or table salt. Bohr model diagram of a chlorine atom showing a central nucleus with red and yellow spheres for protons and neutrons, surrounded by three electron orbits with blue electrons.
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Periodic table of the elements. Left column indicates the subshells that are being filled as atomic number Z increases. The body of the table shows element symbols and Z. analysis and measurement
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halogen: References & Edit History

Additional Reading

N.N. Greenwood and Alan Earnshaw, Chemistry of the Elements, 2nd ed. (1997); and A.F. Holleman, Egon Wiberg, and Nils Wiberg, Inorganic Chemistry (2001), contain well-written chapters on all the halogens. A.P. Hagen and Jerry J. Zuckerman (ed.), The Formation of Bonds to Halogens, 2 vol. (1989–91), covers halogenation and bond formation.

Viktor Gutmann Karl Christe Stefan Schneider

Article Contributors

Primary Contributors

  • Karl Christe
    Research Professor of Chemistry, Department of Chemistry, University of Southern California, Los Angeles, Calif.
  • Viktor Gutmann
  • Stefan Schneider
    Senior Research Scientist, Air Force Research Laboratory, Edwards Air Force Base, Calif.

Other Encyclopedia Britannica Contributors

Article History

Type Description Contributor Date
Add new Web site: Loyola Marymount University Pressbooks - General Chemistry 3e: OER for Inclusive Learning - Occurrence, Preparation, and Properties of Halogens. Nov 12, 2026
Add new Web site: Frontiers - Frontiers in Chemistry - The study of halogen effect on the reactivity of the serine-targeting covalent warheads. Feb 06, 2026
Add new Web site: Chemistry LibreTexts - Group 17- The Halogens. Jul 09, 2025
Questions and answers added. Feb 06, 2025
Add new Web site: ACS Publications - Chemical Reviews - The Halogen Bond. Dec 20, 2024
Add new Web site: National Center for Biotechnology Information - PubMed Central - Halogen gas exposure: Toxic effects on the parturient. Oct 16, 2023
Add new Web site: OpenStax - Chemistry 2e - Occurrence, Preparation, and Properties of Halogens. Sep 05, 2023
Add new Web site: Purdue University - Chemical Education Division Groups - The Chemistry of the Halogens. May 01, 2022
Added cross-references throughout. Oct 23, 2020
Media added. Oct 23, 2020
Changed article title from "halogen element" to "halogen." Apr 02, 2019
Add new Web site: The Periodic Table - Halogen. Feb 28, 2019
Add new Web site: Chemistry LibreTexts - The Halogens. Nov 03, 2017
Add new Web site: Annenberg Learner - Halogen. Jan 12, 2017
Changed "element 117" to "tennessine." Dec 12, 2016
Add new Web site: Buzzle.com - Halogen. Apr 11, 2013
Add new Web site: Rader's Chem4Kids.Com - Halogen. Apr 11, 2013
Updated for discovery of new halogen element, element 117. Apr 08, 2010
Article revised. Jan 29, 2009
Bibliography revised. Jan 29, 2009
Bibliography revised. May 05, 2008
Article revised and updated. May 05, 2008
Added new Web site: Chemical Elements.com - An Interactive Periodic Table of the Elements. Aug 10, 2006
Added new Web site: Chemical Elements.com - An Interactive Periodic Table of the Elements. Aug 10, 2006
Article revised. Aug 25, 2000
Article added to new online database. Jul 26, 1999
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