Beryllium

4 lithium ← beryllium → boron - ↑ Be ↓ Mg periodic table
General
Name, Symbol, Number	beryllium, Be, 4
Chemical series	alkaline earth metals
Group, Period, Block	2, 2, s
Appearance	white-gray metallic
Atomic mass	9.012182(3) g/mol
Electron configuration	1s2 2s2
Electrons per shell	2, 2
Physical properties
Phase	solid
Density (near r.t.)	1.85 g/cm³
Liquid density at m.p.	1.690 g/cm³
Melting point	1560 K (1287 °C, 2349 °F)
Boiling point	2742 K (2469 °C, 4476 °F)
Heat of fusion	7.895 kJ/mol
Heat of vaporization	297 kJ/mol
Heat capacity	(25 °C) 16.443 J/(mol·K)
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 1462 1608 1791 2023 2327 2742
Atomic properties
Crystal structure	hexagonal
Oxidation states	2 (amphoteric oxide)
Electronegativity	1.57 (Pauling scale)
Ionization energies (more)	1st: 899.5 kJ/mol
	2nd: 1757.1 kJ/mol
	3rd: 14848.7 kJ/mol
Atomic radius	105 pm
Atomic radius (calc.)	112 pm
Covalent radius	90 pm
Miscellaneous
Magnetic ordering	diamagnetic
Electrical resistivity	(20 °C) 35.6 nΩ·m
Thermal conductivity	(300 K) 200 W/(m·K)
Thermal expansion	(25 °C) 11.3 µm/(m·K)
Speed of sound (thin rod)	(r.t.) 12870 m/s
Speed of sound (thin rod)	(r.t.) 287 m/s
Shear modulus	132 GPa
Bulk modulus	130 GPa
Poisson ratio	0.032
Mohs hardness	5.5
Vickers hardness	1670 MPa
Brinell hardness	600 MPa
CAS registry number	7440-41-7
Notable isotopes
Main article: Isotopes of beryllium iso NA half-life DM DE (MeV) DP 7Be syn 53.12 d ε - 7Li γ 0.477 - 9Be 100% Be is stable with 5 neutrons 10Be trace 1.51×106 y β- 0.556 10B

Beryllium (chemical symbol Be, atomic number 4) ranks among the lightest of all known metals. Steel-gray in color, it is strong but brittle and is classified as an alkaline earth metal.

• A bivalent element
• primarily used as a hardening agent in alloys (most notably beryllium copper).

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From USGS: "Beryllium (Be) is one of the lightest of all metals and has one of the highest melting points of any light metal. Beryllium metal is used principally in aerospace and defense applications because of its stiffness, light weight, and dimensional stability over a wide temperature range. Beryllium-copper alloys are used in a wide variety of applications because of their electrical and thermal conductivity, high strength and hardness, good corrosion and fatigue resistance, and nonmagnetic properties. Beryllium oxide is an excellent heat conductor, with high strength and hardness, and acts as an electrical insulator in some applications. The United States, one of only three countries that process beryllium ores and concentrates into beryllium products, supplies most of the rest of the world with these products."

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Occurrence

Beryllium ore.

Beryllium is a significant constituent of about 100 minerals. The most important of these are beryl (Al₂Be₃Si₆O₁₈), bertrandite (Be₄Si₂O₇(OH)₂), chrysoberyl (Al₂BeO₄), and phenakite (Be₂SiO₄). Precious forms of beryl are aquamarine and emerald.

The main commercial sources of beryllium and its compounds are beryl and bertrandite. Beryllium metal did not become readily available until 1957. Currently, the chief method of production is by reducing beryllium fluoride with magnesium metal. The chemical reaction can be written in terms of the following equation.

BeF₂ + Mg → MgF₂ + Be

Etymology and Discovery

The name beryllium comes from the Greek word beryllos, for "beryl." That, in turn, can be traced back to the Prakrit veruliya, from Pāli veuriya. These words appear akin to the Tamil veliru or vilar, meaning "to whiten, become pale." At one time, beryllium was referred to as glucinium (from the Greek word glykys, meaning "sweet"), based on the sweet taste of its salts.

Beryllium was discovered by Louis Vauquelin in 1798, as the oxide in beryl and emeralds. In 1828, Friedrich Wöhler and Antoine Bussy independently isolated the metal by reacting potassium with beryllium chloride.

Notable characteristics

Among the light metals, beryllium has one of the highest melting points. Its modulus of elasticity (measure of its elasticity) is approximately one-third more than that of steel. It is nonmagnetic and an excellent conductor of heat. The speed of sound in beryllium is about 12,500 meters per second—greater than that through any other element. Highly permeable to X rays, it liberates neutrons when struck by alpha particles, such as from radium or polonium.

Beryllium resists attack by concentrated nitric acid. In addition, at standard temperature and pressure (0°C, 100 kPa), it resists oxidation when exposed to air. It appears, however, that its ability to scratch glass may be due to the formation of a thin layer of its oxide.

Isotopes

Beryllium has 10 isotopes, of which only ⁹Be is stable. The isotope ¹⁰Be is produced in the atmosphere by the impact of cosmic rays on oxygen and nitrogen. Given that beryllium dissolves in water at pH below 5.5, the isotope ¹⁰Be readily dissolves in rainwater (which generally has a pH less than 5) and is transported to the Earth's surface. As the precipitation quickly becomes more alkaline, ¹⁰Be drops out of solution and accumulates at the soil surface. Based on its long half-life of 1.51 million years, this isotope has a long residence time, before it decays to ¹⁰B (an isotope of boron).

The isotope ¹⁰Be and its daughter products have been used to examine soil erosion, soil formation from regolith, and the development of lateritic soils. It has also been used to check variations in solar activity and the age of ice cores.

The instability of the isotopes ⁷Be and ⁸Be has profound consequences for cosmological theory. It means that elements heavier than beryllium could not be produced by nuclear fusion at the time of the Big Bang. Moreover, the nuclear energy levels of ⁸Be are such that carbon can be produced within stars, thus making it possible for the eventual development of living organisms.

The shortest-lived isotope of beryllium is ¹³Be, which has a half-life of 2.7 × 10^-21 seconds and decays through neutron emission. The isotope ⁶Be also is also very short-lived, with a half-life of 5.0 × 10^-21 seconds.

Applications

A square beryllium foil mounted in a steel case is ready to be used as a window between a vacuum chamber and an X-ray microscope. Beryllium filters out visible light but is highly transparent to X rays.

• Beryllium is used by the defense and aerospace industries in the production of lightweight structural materials for high-speed aircraft, missiles, space vehicles, and communication satellites.
• Beryllium-copper alloys have a wide variety of applications, including the manufacture of spot-welding electrodes, springs, non-sparking tools, and electrical contacts. These applications are based on several properties of the alloys: their ability to absorb large amounts of heat, good electrical and thermal conductivity, high strength and hardness, nonmagnetic properties, and good resistance to corrosion and fatigue.
• Thin sheets of beryllium foil are used with X-ray detection diagnostics, as the foil can filter out visible light and allow only X rays to pass through.
• In the field of X-ray lithography, beryllium is used for the reproduction of microscopic integrated circuits.
• In the telecommunications industry, beryllium is made into tools that can be safely used for tuning the highly magnetic klystrons (specialized vacuum tubes) employed in high-power microwave transmissions.
• The nuclear power industry uses this metal in nuclear reactors as a neutron reflector and moderator.
• Beryllium is used in nuclear weapons for similar reasons. For example, the critical mass of a plutonium sphere is significantly reduced if the plutonium is surrounded by a beryllium shell.
• Beryllium is sometimes used in neutron sources, in which the beryllium is mixed with an alpha emitter such as ²¹⁰Po, ²²⁶Ra, ²³⁹Pu, or ²⁴¹Am.
• Beryllium is also used in making gyroscopes, various computer components, watch springs, and instruments, where lightweight materials with rigidity and dimensional stability are needed.
• Beryllium oxide is useful for applications that require an excellent heat conductor and electrical insulator, with a very high melting point and high strength and hardness.
• Beryllium compounds were once used in fluorescent lighting tubes, but this use was discontinued after workers manufacturing the tubes were found to suffer from berylliosis (see below).
• The James Webb Space Telescope (JWST) will have 18 hexagonal beryllium sections for its mirrors. Because JWST will face a temperature of −240 degrees Celsius (30 kelvin), the mirror is made of beryllium, a material capable of handling extreme cold better than glass. Beryllium contracts and deforms less than glass and remains more uniform at such temperatures.
• Beryllium is also used in the Joint European Torus fusion research facility, to condition the plasma facing components.

Health effects

Beryllium, its alloys, and its salts are toxic and can lead to two groups of conditions: acute beryllium disease and chronic beryllium disease. These diseases affect different tissues and organs, depending on the type of exposure. In particular, inhaling the dust or fumes of beryllium or its compounds can damage the lungs; direct contact can injure the eyes and skin. Beryllium can also adversely affect the heart, liver, kidneys, lymphatic system, and nervous system.

The acute diseases are those that develop after a short, heavy exposure and last for no more than a year. Depending on the type of exposure, an acute beryllium disease may involve inflammation of the skin (contact dermatitis), nose and throat (nasopharyngitis), windpipe (tracheobronchitis), or lungs (pneumonitis).

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Precautions

Beryllium and its salts are toxic and potentially carcinogenic. Prolonged exposure to beryllium and inhalation of its dust can lead to lung diseases such as chemical pneumonitis, berylliosis, and lung cancer. Acute 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 lamps in Massachusetts, and the use of beryllium compounds in fluorescent lighting tubes was discontinued in 1949. The potential for exposure to beryllium exists in the nuclear and aerospace industries, the refining of beryllium metal, melting of beryllium-containing alloys, the manufacture of electronic devices, and the handling of other beryllium-containing materials.

Early researchers tasted beryllium and its various compounds for sweetness, to verify its presence. Modern diagnostic equipment no longer necessitates this highly risky procedure, and no attempt should be made to ingest this substance. Beryllium and its compounds should be handled with great care, and special precautions must be taken when carrying out any activity that could result in the release of beryllium dust. 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. This technique, in which beryllium is bound to a fluorescent chemical (sulfonated hydroxybenzoquinoline), enables the detection of beryllium at concentrations up to 10 times below the recommended limit for the workplace.

Inhalation

Beryllium can be harmful if inhaled and the effects depend on period of exposure. If beryllium air levels are high enough (greater than 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 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. 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 becomes the major site where the immune system responds. The lungs become inflamed, filled with large numbers of white blood cells that accumulate wherever beryllium particles are found. The cells form balls around the beryllium particles called "granulomas." When enough of these granulomas 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 the diet. Beryllium contact with skin that has been scraped or cut may cause rashes or 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 limits

Typical levels of beryllium that industries may release into the air are of the order of 0.01 µg/m³, averaged over a 30-day period, or 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 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 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

• Chemical element
• Periodic table

References

ISBN links support NWE through referral fees

• Los Alamos National Laboratory – Beryllium

• USGS: Beryllium Statistics and Information

• Canadian Centre for Occupational Health and Safety: Beryllium Disease

• 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 Change ACGIH® Publication #7NIC-042

External links

• Computational Chemistry Wiki
• It's Elemental – Beryllium
• National Pollutant Inventory - Beryllium and compounds
• WebElements.com – Beryllium

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