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Beryllium

Beryllium

Gist

Beryllium is a chemical element with the symbol Be and atomic number 4. It's a relatively rare, hard, and lightweight alkaline earth metal known for its high strength-to-weight ratio and stiffness. Beryllium is used in various applications, including aerospace, nuclear reactors, and precision instruments, due to its unique properties.

Beryllium is a chemical element with the symbol Be and atomic number 4. It is a hard, strong, lightweight, and brittle alkaline earth metal, typically a steel-gray color. It's known for its high melting point, good electrical and thermal conductivity, and transparency to X-rays. Beryllium is used in a variety of high-tech applications, including aerospace components, nuclear reactors, and electronics.

Summary

Beryllium is a chemical element; it has symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form minerals. Gemstones high in beryllium include beryl (aquamarine, emerald, red beryl) and chrysoberyl. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars, beryllium is depleted as it is fused into heavier elements. Beryllium constitutes about 0.0004 percent by mass of Earth's crust. The world's annual beryllium production of 220 tons is usually manufactured by extraction from the mineral beryl, a difficult process because beryllium bonds strongly to oxygen.

In structural applications, the combination of high flexural rigidity, thermal stability, thermal conductivity and low density (1.85 times that of water) make beryllium a desirable aerospace material for aircraft components, missiles, spacecraft, and satellites. Because of its low density and atomic mass, beryllium is relatively transparent to X-rays and other forms of ionizing radiation; therefore, it is the most common window material for X-ray equipment and components of particle detectors. When added as an alloying element to aluminium, copper (notably the alloy beryllium copper), iron, or nickel, beryllium improves many physical properties. For example, tools and components made of beryllium copper alloys are strong and hard and do not create sparks when they strike a steel surface. In air, the surface of beryllium oxidizes readily at room temperature to form a passivation layer 1–10 nm thick that protects it from further oxidation and corrosion. The metal oxidizes in bulk (beyond the passivation layer) when heated above 500 °C (932 °F), and burns brilliantly when heated to about 2,500 °C (4,530 °F).

The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease, berylliosis, in some people. Berylliosis is typically manifested by chronic pulmonary fibrosis and, in severe cases, right sided heart failure and death.

Details

Beryllium (Be), chemical element, the lightest member of the alkaline-earth metals of Group 2 (IIa) of the periodic table, used in metallurgy as a hardening agent and in many outer space and nuclear applications.

Element Properties

atomic number  :  4
atomic weight  :  9.0121831
melting point  :  1,287 °C (2,349 °F)
boiling point  :  2,471 °C (4,480 °F)
specific gravity  :  1.85 at 20 °C (68 °F)
oxidation state  :  +2

Occurrence, properties, and uses

Beryllium is a steel-gray metal that is quite brittle at room temperature, and its chemical properties somewhat resemble those of aluminum. It does not occur free in nature. Beryllium is found in beryl and emerald, minerals that were known to the ancient Egyptians. Although it had long been suspected that the two minerals were similar, chemical confirmation of this did not occur until the late 18th century. Emerald is now known to be a green variety of beryl. Beryllium was discovered (1798) as the oxide by French chemist Nicolas-Louis Vauquelin in beryl and in emeralds and was isolated (1828) as the metal independently by German chemist Friedrich Wöhler and French chemist Antoine A.B. Bussy by the reduction of its chloride with potassium. Beryllium is widely distributed in Earth’s crust and is estimated to occur in Earth’s igneous rocks to the extent of 0.0002 percent. Its cosmic abundance is 20 on the scale in which silicon, the standard, is 1,000,000. The United States has about 60 percent of the world’s beryllium and is by far the largest producer of beryllium; other major producing countries include China, Mozambique, and Brazil.

There are about 30 recognized minerals containing beryllium, including beryl (Al2Be3Si6O18, a beryllium aluminum silicate), bertrandite (Be4Si2O7(OH)2, a beryllium silicate), phenakite (Be2SiO4), and chrysoberyl (BeAl2O4). (The precious forms of beryl, emerald and aquamarine, have a composition closely approaching that given above, but industrial ores contain less beryllium; most beryl is obtained as a by-product of other mining operations, with the larger crystals being picked out by hand.) Beryl and bertrandite have been found in sufficient quantities to constitute commercial ores from which beryllium hydroxide or beryllium oxide is industrially produced. The extraction of beryllium is complicated by the fact that beryllium is a minor constituent in most ores (5 percent by mass even in pure beryl, less than 1 percent by mass in bertrandite) and is tightly bound to oxygen. Treatment with acids, roasting with complex fluorides, and liquid-liquid extraction have all been employed to concentrate beryllium in the form of its hydroxide. The hydroxide is converted to fluoride via ammonium beryllium fluoride and then heated with magnesium to form elemental beryllium. Alternatively, the hydroxide can be heated to form the oxide, which in turn can be treated with carbon and chlorine to form beryllium chloride; electrolysis of the molten chloride is then used to produce the metal. The element is purified by vacuum melting.

Beryllium is the only stable light metal with a relatively high melting point. Although it is readily attacked by alkalies and nonoxidizing acids, beryllium rapidly forms an adherent oxide surface film that protects the metal from further air oxidation under normal conditions. These chemical properties, coupled with its excellent electrical conductivity, high heat capacity and conductivity, good mechanical properties at elevated temperatures, and very high modulus of elasticity (one-third greater than that of steel), make it valuable for structural and thermal applications. Beryllium’s dimensional stability and its ability to take a high polish have made it useful for mirrors and camera shutters in space, military, and medical applications and in semiconductor manufacturing. Because of its low atomic weight, beryllium transmits X-rays 17 times as well as aluminum and has been extensively used in making windows for X-ray tubes. Beryllium is fabricated into gyroscopes, accelerometers, and computer parts for inertial guidance instruments and other devices for missiles, aircraft, and space vehicles, and it is used for heavy-duty brake drums and similar applications in which a good heat sink is important. Its ability to slow down fast neutrons has found considerable application in nuclear reactors.

Much beryllium is used as a low-percentage component of hard alloys, especially with copper as the main constituent but also with nickel- and iron-based alloys, for products such as springs. Beryllium-copper (2 percent beryllium) is made into tools for use when sparking might be dangerous, as in powder factories. Beryllium itself does not reduce sparking, but it strengthens the copper (by a factor of 6), which does not form sparks upon impact. Small amounts of beryllium added to oxidizable metals generate protecting surface films, reducing inflammability in magnesium and tarnishing in silver alloys.

Neutrons were discovered (1932) by British physicist Sir James Chadwick as particles ejected from beryllium bombarded by alpha particles from a radium source. Since then beryllium mixed with an alpha emitter such as radium, plutonium, or americium has been used as a neutron source. The alpha particles released by radioactive decay of radium atoms react with atoms of beryllium to give, among the products, neutrons with a wide range of energies—up to about 5 × 106 electron volts (eV). If radium is encapsulated, however, so that none of the alpha particles reach beryllium, neutrons of energy less than 600,000 eV are produced by the more-penetrating gamma radiation from the decay products of radium. Historically important examples of the use of beryllium/radium neutron sources include the bombardment of uranium by German chemists Otto Hahn and Fritz Strassmann and Austrian-born physicist Lise Meitner, which led to the discovery of nuclear fission (1939), and the triggering in uranium of the first controlled-fission chain reaction by Italian-born physicist Enrico Fermi (1942).

The only naturally occurring isotope is the stable beryllium-9, although 11 other synthetic isotopes are known. Their half-lives range from 1.5 million years (for beryllium-10, which undergoes beta decay) to {6.7} × {10}^{-17} second for beryllium-8 (which decays by two-proton emission). The decay of beryllium-7 (53.2-day half-life) in the Sun is the source of observed solar neutrinos.

Additional Information:

Appearance

Beryllium is a silvery-white metal. It is relatively soft and has a low density.

Uses

Beryllium is used in alloys with copper or nickel to make gyroscopes, springs, electrical contacts, spot-welding electrodes and non-sparking tools. Mixing beryllium with these metals increases their electrical and thermal conductivity.

Other beryllium alloys are used as structural materials for high-speed aircraft, missiles, spacecraft and communication satellites.

Beryllium is relatively transparent to X-rays so ultra-thin beryllium foil is finding use in X-ray lithography. Beryllium is also used in nuclear reactors as a reflector or moderator of neutrons.

The oxide has a very high melting point making it useful in nuclear work as well as having ceramic applications.

Biological role

Beryllium and its compounds are toxic and carcinogenic. If beryllium dust or fumes are inhaled, it can lead to an incurable inflammation of the lungs called berylliosis.

Natural abundance

Beryllium is found in about 30 different mineral species. The most important are beryl (beryllium aluminium silicate) and bertrandite (beryllium silicate). Emerald and aquamarine are precious forms of beryl.

The metal is usually prepared by reducing beryllium fluoride with magnesium metal.

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