Halide

<h2 id="reactions">Reactions</h2>
<h3>Redox</h3>
<p>Halides cannot be reduced under the usual laboratory conditions, but they all can be oxidized to the parent halogens, which are <a href="/facts/Diatomic/hkfKAC7m">diatomic</a>.  Especially for iodide and less so for the lighter halides, intermediates can be observed and isolated.  Best characterized is <a href="/facts/Triiodide/fNgW9WEr">triiodide</a>.  Many related species are known, including a host of <a href="/facts/Polyiodide/uyYUvm37">polyiodides</a>.
</p>
<h3>Protonation</h3>
<p>Halides are conjugate bases of <a href="/facts/Hydrogen_halide/avUQ6Nwy">hydrogen halides</a>, which are all gases.  When the protonation is conducted in aqueous solution, <a href="/facts/Hydrohalic_acid/avUQ6Nwy">hydrohalic acids</a> are produced.
</p>
<h3>Reaction with silver ions</h3>
<p>Halide salts such as <a href="/facts/Potassium_chloride/RgT2MdPa">KCl</a>, <a href="/facts/Potassium_bromide/mGWPW1zd">KBr</a> and <a href="/facts/Potassium_iodide/6023uFnx">KI</a> are highly soluble in water to give colorless solutions. The solutions react readily with a solution of <a href="/facts/Silver_nitrate/U5w4A3DN">silver nitrate</a> AgNO3. These three halides form solid <a href="/facts/Precipitate/s3BgsLLY">precipitates</a>:<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p>
<ul><li><a href="/facts/Silver_chloride/qSbcrlqq">AgCl</a>: white</li>
<li><a href="/facts/Silver_bromide/5YsSDplb">AgBr</a>: pale yellow</li>
<li><a href="/facts/Silver_iodide/lMYrbatr">AgI</a>: yellow</li></ul>
<p>Similar but slower reactions occur with <a href="/facts/Alkyl_halide/Enb7LQqt">alkyl halides</a> in place of alkali metal halides, as described in the <a href="/facts/Beilstein_test/Lb6QAGDP">Beilstein test</a>.
</p>
<h2 id="uses">Uses</h2>
<p>Metal halides are used in <a href="/facts/High-intensity_discharge_lamp/T7179PrP">high-intensity discharge lamps</a> called <a href="/facts/Metal_halide_lamp/kxCKb1E9">metal halide lamps</a>, such as those used in  modern <a href="/facts/Street_light/Uuw2oH1y">street lights</a>.  These are more <a href="/facts/Energy_conversion_efficiency/gSqXlWoI">energy-efficient</a> than <a href="/facts/Mercury-vapor_lamp/cVCl1CSY">mercury-vapor lamps</a>, and have much better <a href="/facts/Colour_rendition/aaIJkcRn">colour rendition</a> than <a href="/facts/Orange_(colour)/FNScAQvv">orange</a> <a href="/facts/Sodium-vapor_lamp/STEH8FgR">high-pressure sodium lamps</a>. Metal halide lamps are also commonly used in <a href="/facts/Greenhouse/VBHMUgfM">greenhouses</a> or in rainy climates to supplement natural <a href="/facts/Sunlight/WPkJRC7s">sunlight</a>.
</p><p><a href="/facts/Silver_halide/uM8V4wJc">Silver halides</a> are used in <a href="/facts/Photographic_film/37aFq6ls">photographic films</a> and <a href="/facts/Photographic_paper/7P6Q8H6D">papers</a>. When the film is <a href="/facts/Photographic_processing/6VTxcPMA">developed</a>, the silver halides which have been exposed to light are reduced to metallic silver, forming an image.
</p><p>Halides are also used in <a href="/facts/Flux_(metallurgy)/ruKFTPGD">solder paste</a>, commonly as a Cl or Br equivalent.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p><p>Synthetic <a href="/facts/Organic_chemistry/djxhxaNg">organic chemistry</a> often incorporates halogens into <a href="/facts/Organohalide/FTmWVdPT">organohalide</a> compounds.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Salinity/X6mB1YAM">Salinity</a></li>
<li><a href="/facts/Organohalide/FTmWVdPT">Organohalide</a></li>
<li><a href="/facts/Hydrogen_halide/avUQ6Nwy">Hydrogen halide</a></li>
<li><a href="/facts/Silver_halide/uM8V4wJc">Silver halide</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Definition of HALOGENIDE". www.merriam-webster.com. Retrieved 2022-01-07. <a href="https://www.merriam-webster.com/dictionary/halogenide" target="_blank">https://www.merriam-webster.com/dictionary/halogenide</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Greenwood, Norman  N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 82. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Greenwood, Norman  N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 694. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Greenwood, Norman  N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1184. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Halogen-Free Solder Paste" (PDF). Archived from the original (PDF) on 2012-03-17. Retrieved 2011-03-21. <a href="https://web.archive.org/web/20120317004413/http://www.indium.com/halogen-free/assets/PDF/Indium8_9HF_Overview.pdf" target="_blank">https://web.archive.org/web/20120317004413/http://www.indium.com/halogen-free/assets/PDF/Indium8_9HF_Overview.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Halide open-in-new

Halide