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==Overview==
'''Beryllium''' ({{pronEng|bəˈrɪliəm}}) is a [[chemical element]] with the symbol '''Be''' and [[atomic number]] 4. A  [[Bivalent (chemistry)|bivalent]] element, beryllium is a steel grey, strong, light-weight yet brittle, [[alkaline earth]] [[metal]]. It is primarily used as a hardening agent in [[alloy]]s, most notably [[beryllium copper]].

== Properties ==
*It has one of the highest [[melting point]]s of the [[light metal]]s. The [[modulus of elasticity]] of beryllium is approximately <sup>1</sup>/<sub>3</sub> greater than that of steel. It has excellent [[thermal conductivity]], conducts sound with the highest velocity of any solid [http://www.sizes.com/natural/sound.htm], and is nonmagnetic. 
*It is highly permeable to [[X-ray]]s, and [[neutron]]s are liberated when it is hit by [[alpha particle]]s, as from [[radium]] or [[polonium]] (about 30 neutrons/million alpha particles). 
*At [[standard temperature and pressure]]s beryllium resists [[oxidation]] when exposed to air (although its ability to scratch glass is probably due to the formation of a thin layer of the oxide).It resists attack by concentrated [[nitric acid]].

==History==
This element was discovered by [[Louis-Nicolas Vauquelin]] in [[1798]] as the oxide in [[beryl]] and in [[emerald]]s. [[Friedrich Woehler|Friedrich Wöhler]] and [[Antoine Bussy|A. A. Bussy]] independently isolated the metal in [[1828]] by reacting [[potassium]] and [[beryllium chloride]].

== Etymology ==
The name beryllium comes from the [[Greek language|Greek]] ''βερυλλος'', ''beryllos'', ''beryl'', from [[Prakrit]] ''veruliya'', from [[Pāli]] ''veuriya''; akin or perhaps akin to [[Tamil language]] ''veiru'' or, ''viar'', "to become pale," in reference to the pale semiprecious gemstone [[beryl]]<ref>http://www.bartleby.com/61/74/B0207400.html</ref> At one time beryllium was referred to as '''glucinium''' (from [[Greek language|Greek]], sweet), due to the sweet taste of its [[salt]]s (with the accompanying chemical symbol "'''Gl'''"<ref> Black, The MacMillian Company, New York, 1937</ref>) .

== Applications ==
===Mechanical===
* Due to its stiffness, light weight, and dimensional stability over a wide temperature range, Beryllium metal is used in the defense and aerospace industries as light-weight structural materials in high-speed aircraft, missiles, space vehicles, and [[communication satellite]]s. For example, many high-quality liquid fueled rockets use nozzles of pure Be, an example being the [[Saturn V]].
* Beryllium is used as an [[alloy]]ing agent in the production of [[beryllium copper]], which contains up to 2.5% beryllium. Beryllium-copper alloys are used in a wide variety of applications because of their combination of high [[electrical conductivity|electrical]] and [[thermal conductivity]], high strength and [[Hardness (materials science)|hardness]], nonmagnetic properties, along with good corrosion and fatigue resistance. These applications include the making of spot-[[welding]] electrodes, [[Spring (device)|springs]], non-sparking tools and [[electrical contact]]s.
* In the [[telecommunications]] industry, tools made of beryllium are used to tune the highly magnetic [[klystron]]s used for high power [[microwave]] applications. 
* Beryllium copper is used in electrical spring contacts.
* Beryllium is used in the making of [[gyroscope]]s, [[computer]] equipment, watch springs and instruments where light-weight, rigidity and dimensional stability are needed.
* The [[James Webb Space Telescope]]<ref>[http://www.jwst.nasa.gov/mirror.html Beryllium related details from NASA]</ref> will have 18 hexagonal beryllium sections for its mirrors. Because JWST will face a temperature of &minus;240 degrees Celsius (33 [[kelvin]]s), the mirror is made of beryllium, a material capable of handling extreme cold better than glass. Beryllium contracts and deforms less than glass &mdash; and thus remains more uniform &mdash; in such temperatures. For the same reason, the optics of the [[Spitzer Space Telescope]] are entirely built of beryllium metal.
* Beryllium has been used in [[tweeter]] and [[Mid-range speaker|mid-range]] audio [[loudspeaker]] construction as an alternative to [[titanium]] and [[aluminium]], largely due to its lower density and greater rigidity.
===Radiation===
[[Image:Be foil square.jpg|thumb|left|250px|A square beryllium foil mounted in a steel case to be used as a window between a vacuum chamber and an [[X-ray microscope]]. Beryllium, due to its low [[Atomic number|Z number]] is highly transparent to X-rays.]]
* Thin sheets of beryllium foil are used as windows in [[X-ray]] detectors to filter out visible light and allow only X-rays to be detected.
* Sheets of beryllium ranging from {{convert|3|mm|in}} thick down to {{convert|25|µm|in}} thick are used as the output window in x-ray tubes, allowing x-rays to leave the tube while keeping a vacuum on the inside of the tube.
* In the field of [[X-ray lithography]] beryllium is used for the reproduction of microscopic [[integrated circuit]]s.
* Because of its low [[atomic number]] beryllium is almost transparent to energetic electrically charged [[Elementary particle|particles]]. Therefore it is used to build the [[beamline|beam pipe]] around the collision region in [[collider]] [[particle physics]] experiments. Notably all four main detector experiments at the [[Large Hadron Collider]] accelerator ([[A Large Ion Collider Experiment|ALICE]], [[ATLAS experiment|ATLAS]], [[Compact Muon Solenoid|CMS]], [[LHCb]]) use a beryllium beam-pipe.

===Nuclear===
* Beryllium is a good [[neutron moderator]] because it has a low [[neutron absorption]] [[Neutron cross-section|cross section]], and because light nuclei are more effective at slowing down neutrons than heavy nuclei. It has been used in some [[nuclear reactor]]s; see [[:Category:Beryllium moderated reactors]].
* Beryllium is used in [[nuclear weapon design]]s, where it is a good [[nuclear weapon design#Pusher|pusher]] and the best possible neutron [[nuclear weapon design#Reflector|reflector]], reducing the [[critical mass]] needed for a [[fission]] [[chain reaction]], while adding relatively little mass to the weapon itself. It is a poor [[nuclear weapon design#Tamper|tamper]] because of its low mass, but tamping is less important in fusion-[[boosted fission weapon]]s. Its transparency to X-rays also lets the energy from a primary fission explosion escape for use in [[radiation implosion]] of a secondary fusion stage.
* Beryllium is sometimes used in [[neutron source]]s, in which the beryllium is mixed with an alpha emitter such as <sup>210</sup>[[polonium|Po]], <sup>226</sup>[[radium|Ra]], <sup>239</sup>[[plutonium|Pu]] or <sup>241</sup>[[americium|Am]].
* Beryllium is used in the [[Joint European Torus]] [[nuclear fusion|fusion]] research facility and will be used in [[ITER]], to condition the plasma facing components.<ref>http://www.jet.efda.org/pages/focus/011fusion-tech/index.html#investigations</ref>

==Compounds==
* Beryllium is an effective p-type dopant in III-V compound semiconductors. It is widely used in materials such as GaAs, AlGaAs, InGaAs, and InAlAs grown by molecular beam epitaxy (MBE).
* [[Beryllium oxide]] is useful for many applications that require an excellent heat conductor, with high strength and hardness, with a very high melting point, and that acts as an electrical insulator. It is being studied for use in increasing the [[thermal conductivity]] of [[uranium dioxide]] [[nuclear fuel]] pellets.<ref>http://news.uns.purdue.edu/UNS/html4ever/2005/050927.Solomon.nuclear.html</ref>
* Beryllium compounds were once used in [[fluorescent light]]ing tubes, but this use was discontinued because of [[berylliosis]] in the workers manufacturing the tubes (see below).
''See also [[:category:Beryllium compounds|Beryllium compounds]]''.

== Occurrence on Earth ==
Beryllium is an essential constituent of about 100 out of about 4000 known [[mineral]]s, the most important of which are [[bertrandite]] (Be<sub>4</sub>Si<sub>2</sub>O<sub>7</sub>(OH)<sub>2</sub>), [[beryl]] (Al<sub>2</sub>Be<sub>3</sub>Si<sub>6</sub>O<sub>18</sub>), [[chrysoberyl]] (Al<sub>2</sub>BeO<sub>4</sub>), and [[phenakite]] (Be<sub>2</sub>SiO<sub>4</sub>). Precious forms of beryl are [[aquamarine]] and [[emerald]].

The most important commercial sources of beryllium and its compounds are beryl and bertrandite. Beryllium metal did not become readily available until [[1957]]. Currently, most production of this metal is accomplished by reducing [[beryllium fluoride]] with [[magnesium]] metal. The price on the US market for vacuum-cast beryllium ingots was 338 [[United States dollar|US$]] per pound ($745/kg) in 2001.<ref>http://minerals.usgs.gov/minerals/pubs/commodity/beryllium/</ref> 

:BeF<sub>2</sub> + Mg → MgF<sub>2</sub> + Be

''See also [[:category:Beryllium minerals|beryllium minerals]].''

== Isotopes ==
Of beryllium's [[isotope]]s, only <sup>9</sup>Be is stable. [[Cosmogenic]] <sup>10</sup>Be is produced in the [[Earth's atmosphere|atmosphere]] by [[cosmic ray spallation]] of [[oxygen]] and [[nitrogen]]. Because beryllium tends to exist in [[solution]]s below about [[pH]] 5.5 (and most rainwater has a pH less than 5), it will dissolve and be transported to the Earth's surface via rainwater. As the [[precipitation (chemistry)|precipitation]] quickly becomes more [[alkaline]], beryllium drops out of solution. Cosmogenic <sup>10</sup>Be thereby accumulates at the [[soil]] surface, where its relatively long [[half-life]] (1.51 million years) permits a long residence time before decaying to <sup>10</sup>[[boron|B]]. <sup>10</sup>Be and its daughter products have been used to examine [[soil erosion]], [[soil formation]] from [[regolith]], the development of [[laterite|lateritic soils]], as well as variations in [[solar activity]] and the age of [[ice core]]s. It is also formed in nuclear explosions by a reaction of fast neutrons with <sup>13</sup>C in the carbon dioxide in air, and is one of the historical indicators of past activity at nuclear test sites.[[Image:Solar Activity Proxies.png|thumb|left|300px|Plot showing variations in solar activity, including variation in <sup>10</sup>Be concentration.]]

The fact that <sup>7</sup>Be and <sup>8</sup>Be are unstable has profound cosmological consequences as it means that elements heavier than beryllium could not be produced by nuclear fusion in the [[Big Bang]]. However, [[Fred Hoyle]] showed that the energy levels of <sup>8</sup>Be and <sup>12</sup>C favour carbon production by the [[triple-alpha process]] in helium burning stars, thus making life possible. (See also [[Big Bang nucleosynthesis]]).

The shortest-lived known isotope of beryllium is <sup>13</sup>Be which decays through [[neutron emission]]. It has a half-life of 2.7&nbsp;&times;&nbsp;10<sup>-21</sup> second. <sup>6</sup>Be is also very short-lived with a half-life of 5.0&nbsp;&times;&nbsp;10<sup>-21</sup> second.

The exotics <sup>11</sup>Be and <sup>14</sup>Be are known to exhibit a [[nuclear halo]].

== Precautions ==
[[Image:Beryllium OreUSGOV.jpg|thumb|left|Beryllium ore]]
According to the [[International Agency for Research on Cancer]] (IARC), beryllium and beryllium compounds are [[List of IARC Group 1 carcinogens|Category 1 carcinogens]]; they are carcinogenic to both animals and humans.<ref>http://www.inchem.org/documents/iarc/vol58/mono58-1.html IARC Monograph, Volume 58, 1993.</ref> Chronic [[berylliosis]] is a [[pulmonary]] and [[systemic circulation|systemic]] [[granulomatous]] disease caused by exposure to beryllium. Acute beryllium disease in the form of [[chemical pneumonitis]] was first reported in Europe in 1933 and in the United States in 1943. Cases of chronic berylliosis were first described in 1946 among workers in plants manufacturing [[fluorescent lamp]]s in [[Massachusetts]]. Chronic berylliosis resembles [[sarcoidosis]] in many respects, and the differential diagnosis is often difficult.

Although the use of beryllium compounds in fluorescent lighting tubes was discontinued in 1949, potential for exposure to beryllium exists in the nuclear and aerospace industries and in the refining of beryllium metal and melting of beryllium-containing alloys, the manufacturing of electronic devices, and the handling of other beryllium-containing material.

Early researchers tasted beryllium and its various compounds for sweetness in order to verify its presence. Modern diagnostic equipment no longer necessitates this highly risky procedure and no attempt should be made to ingest this highly toxic substance. Beryllium and its compounds should be handled with great care and special precautions must be taken when carrying out any activity which could result in the release of beryllium dust ([[lung cancer]] is a possible result of prolonged exposure to beryllium laden dust).

This substance can be handled safely if certain procedures are followed. No attempt should be made to work with beryllium before familiarization with correct handling procedures.

A successful test for beryllium on different surface areas has been recently developed. The procedure uses fluorescence when beryllium is bound to sulfonated hydroxybenzoquinoline to detect up to 10 times lower than the recommended limit for beryllium concentration in the work place. Fluorescence increases with increasing beryllium concentration. The new procedure has been successfully tested on a variety of surfaces.

=== Inhalation ===
Beryllium can be harmful if inhaled and the effects depend on period of exposure. If beryllium concentrations in air are high enough (greater than {{nowrap|100 µg/m³}}), an acute condition can result, called acute beryllium disease, which resembles [[pneumonia]]. Occupational and community air standards are effective in preventing most acute lung damage. Long term exposure to beryllium can increase the risk of developing [[lung cancer]]. The more common and serious health hazard from beryllium today is chronic beryllium disease (CBD), discussed below. It continues to occur in industries as diverse as metal recycling, dental laboratories, alloy manufacturing, nuclear weapons production, defense industries, and metal machine shops that work with alloys containing small amounts of beryllium.

====Chronic beryllium disease (CBD)====
Some people (1-15%) become sensitive to beryllium. These individuals may develop an inflammatory reaction that principally targets the respiratory system and skin. This condition is called chronic beryllium disease (CBD), and can occur within a few months or many years after exposure to higher than normal levels of beryllium (greater than {{nowrap|0.02 µg/m³}}). This disease causes fatigue, weakness, night sweats and can cause difficulty in breathing and a persistent dry cough. It can result in anorexia, weight loss, and may also lead to right-side heart enlargement and heart disease in advanced cases. Some people who are sensitized to beryllium may not have any symptoms. The disease is treatable, but not curable with traditional drugs and medicine. CBD occurs when the body's [[immune system]] recognizes beryllium particles as foreign material and mounts an immune system attack against the particles. Because these particles are typically inhaled into the lungs, the lungs become the major site where the immune system responds, they become inflamed and fill with large numbers of [[white blood cells]] that accumulate wherever beryllium particles are found. These cells form balls around the beryllium particles called “[[granulomas]].”  When enough of these develop, they interfere with the normal function of the organ. Over time, the lungs become stiff and lose their ability to help transfer oxygen from the air into the bloodstream. Patients with CBD develop difficulty inhaling and exhaling sufficient amounts of air, and the amount of oxygen in their bloodstreams falls. Treatment of such patients includes use of oxygen and medicines that try to suppress the immune system’s over-reaction to beryllium. A class of immunosuppressive medicines called [[glucocorticoids]] (example: [[prednisone]]) is most commonly used as treatment. The general population is unlikely to develop acute or chronic beryllium disease because ambient air levels of beryllium are normally very low (0.00003-0.0002 µg/m³).

=== Ingestion ===
Swallowing beryllium has not been reported to cause effects in humans because very little beryllium is absorbed from the stomach and intestines. Ulcers have been seen in dogs ingesting beryllium in their
diet.

=== Dermatological effects ===
Beryllium can cause [[contact dermatitis]]. Beryllium contact with skin that has been scraped or cut may cause [[rash]]es, ulcers, or bumps under the skin called [[granulomas]].

=== Effects on children ===
There are no studies on the health effects of children exposed to beryllium, although individual cases of CBD have been reported in children of beryllium workers from the 1940s. It is likely that the health effects seen in children exposed to beryllium will be similar to the effects seen in adults. It is unknown whether children differ from adults in their susceptibility to beryllium. It is unclear whether beryllium is [[teratogenic]].

=== Detection in the body ===
Beryllium can be measured in the urine and blood. The amount of beryllium in blood or urine may not indicate time or quantity of exposure. Beryllium levels can also be measured in lung and skin samples. While such measurements may help establish that exposure has occurred, other tests are used to determine if that exposure has resulted in health effects. A blood test, the blood beryllium lymphocyte proliferation test (BeLPT), identifies beryllium sensitization and has predictive value for CBD. The BeLPT has become the standard test for detecting beryllium sensitization and CBD in individuals who are suspected of having CBD and to help distinguish it from similar conditions such as sarcoidosis. It is also the main test used in industry health programs to monitor whether disease is occurring among current and former workers who have been exposed to beryllium on the job. The test can detect disease that is at an early stage, or can detect disease at more advanced stages of illness as well. The BeLPT can also be performed using cells obtained from a person's lung by a procedure called "bronchoscopy."

=== Industrial release and occupational exposure limits ===
Typical levels of beryllium that industries may release into the air are of the order of {{nowrap|0.01 µg/m³}}, averaged over a 30-day period, or {{nowrap|2 µg/m³}} of workroom air for an 8-hour work shift. Compliance with the current U.S. [[Occupational Safety and Health Administration]] (OSHA) [[permissible exposure limit]] for beryllium of {{nowrap|2 µg/m³}} has been determined to be inadequate to protect workers from developing beryllium sensitization and CBD. The [[American Conference of Governmental Industrial Hygienists]] (ACGIH), which is an independent organization of experts in the field of occupational health, has proposed a threshold limit value (TLV) of {{nowrap|0.05 µg/m³}} in a 2006 Notice of Intended Change (NIC). This TLV is 40 times lower than the current OHSA permissible exposure limit, reflecting the ACGIH analysis of best available peer-reviewed research data concerning how little airborne beryllium is required to cause sensitization and CBD. Because it can be difficult to control industrial exposures to beryllium, it is advisable to use any methods possible to reduce airborne and surface contamination by beryllium, to minimize the use of beryllium and beryllium-containing alloys whenever possible, and to educate people about the potential hazards if they are likely to encounter beryllium dust or fumes.

== See also ==
*[[:Category:Beryllium compounds]]
*''[[Sucker Bait]]'', a story by [[Isaac Asimov]] in which the health hazard of beryllium dust is an important plot point

== References ==
{{reflist|2}}
*[http://periodic.lanl.gov/elements/4.html Los Alamos National Laboratory &ndash; Beryllium]
* Burrell, AK. Ehler, DS. McClesky, TM. Minogue, EM. Taylor, TP. Development of a New Fluorescence Method for the Detection of Beryllium on Surfaces. Journal of ASTM International (JAI). 2005. Vol 2: Issue 9. http://www.astm.org/cgi-bin/SoftCart.exe/JOURNALS/JAI/PAGES/JAI13168.htm?E+mystore
* Infante PF, Newman LS.  "Commentary: Beryllium exposure and Chronic Beryllium Disease."  ''Lancet'' 2004; 415-16.
* Newman LS. "Beryllium." ''Chemical & Engineering News'', 2003; 36:38.
* Kelleher PC, Martyny JW, Mroz MM, Maier LA, Ruttenber JA, Young DA, Newman LS.  "Beryllium particulate exposure and disease relations in a beryllium machining plant."  ''J Occup Environ Med'' 2001; 43:238-249.
* Mroz MM, Balkissoon R, Newman LS.  "Beryllium."  In: Bingham E, Cohrssen B, Powell C (eds.)  ''Patty’s Toxicology'', Fifth Edition. New York:   John Wiley & Sons 2001, 177-220.
* ''Beryllium and Compounds: TLV® Chemical Substances Draft Documentation, Notice of Intended Chang''e ACGIH® Publication #7NIC-042

== External links ==
{{Commons|Beryllium}}
{{wiktionary|beryllium}}
* [http://www.compchemwiki.org/index.php?title=Beryllium Computational Chemistry Wiki]
* [http://education.jlab.org/itselemental/ele004.html It's Elemental &ndash; Beryllium]
* [http://www.npi.gov.au/database/substance-info/profiles/13.html National Pollutant Inventory - Beryllium and compounds]
* [http://www.webelements.com/webelements/elements/text/Be/index.html WebElements.com &ndash; Beryllium]
* [[MSDS]]:  [http://espi-metals.com/msds's/beryllium.pdf ESPI Metals]
* [http://www.cdc.gov/niosh/topics/beryllium/ National Institute for Occupational Safety and Health – Beryllium Page]

[[Category:Chemical elements]]
[[Category:Alkaline earth metals]]
[[Category:Toxicology]]
[[Category:Beryllium|*]]
[[Category:IARC Group 1 carcinogens]]
[[Category:Neutron moderators]]
[[Category:Nuclear materials]]
[[Category:Occupational safety and health]]

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