Alkaline earth metal
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. …
The mineral beryl, which contains beryllium, has been used at least since the Ptolemaic dynasty of Egypt. The Papyrus Graecus Holmiensis, written in the third or fourth century CE, contains notes on how to prepare artificial emerald and beryl.
Early analyses of emeralds and beryls by Martin Heinrich Klaproth, Torbern Olof Bergman, Franz Karl Achard, and Johann Jakob Bindheim always yielded similar elements, leading to the mistaken conclusion that both substances are aluminium silicates. Mineralogist René Just Haüy discovered that both crystals are geometrically identical, and he asked chemist Louis-Nicolas Vauquelin for a chemical analysis.
In a 1798 paper read before the Institut de France, Vauquelin reported that he found a new "earth" by dissolving aluminium hydroxide from emerald and beryl in an additional alkali. The editors of the journal Annales de chimie et de physique named the new earth "glucine" for the sweet taste of some of its compounds. The name beryllium was first used by Friedrich Wöhler in 1828. Both beryllium and glucinum were used concurrently until 1949, when the IUPAC adopted beryllium as the standard name of the element.
Friedrich Wöhler and Antoine Bussy independently isolated beryllium in 1828 by the chemical reaction of metallic potassium with beryllium chloride, as follows:
BeCl2 + 2 K → 2 KCl + Be
Using an alcohol lamp, Wöhler heated alternating layers of beryllium chloride and potassium in a wired-shut platinum crucible. …
Beryllium is a steel gray and hard metal that is brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional stiffness (Young's modulus 287 GPa) and a melting point of 1287 °C. The modulus of elasticity of beryllium is approximately 35% greater than that of steel. The combination of this modulus and a relatively low density results in an unusually high sound conduction speed in beryllium – about 12.9 km/s at ambient conditions.
Among all metals, beryllium dissipates the most heat per unit weight, with both high specific heat (1925 J·kg−1·K−1) and thermal conductivity (216 W·m−1·K−1).
Beryllium's conductivity and relatively low coefficient of linear thermal expansion (11.4×10−6 K−1) make it uniquely stable under extreme temperature differences.
Naturally occurring beryllium, save for slight contamination by the radioisotopes created by cosmic rays, is isotopically pure beryllium-9, which has a nuclear spin of 3/2−. The inelastic scattering cross section of beryllium increases with relation to neutron energy, allowing for significant slowing of higher-energy neutrons. Therefore, it works as a neutron reflector and neutron moderator; the exact strength of neutron slowing depends on the purity and size of the crystallites in the material.
The isotope 9Be can undergo a (n, 2n) neutron reaction with fast neutrons, to produce 8Be, which almost immediately breaks into two alpha particles. …
Beryllium is found in over 100 minerals, but most are uncommon to rare. The more common beryllium-containing minerals include: bertrandite (Be4Si2O7(OH)2), beryl (Al2Be3Si6O18), chrysoberyl (Al2BeO4) and phenakite (Be2SiO4). Precious forms of beryl are aquamarine, red beryl and emerald.
The green color in gem-quality forms of beryl comes from varying amounts of chromium (about 2% for emerald).
The two main ores of beryllium, beryl and bertrandite, are found in Argentina, Brazil, India, Madagascar, Russia and the United States. Total world reserves of beryllium ore are greater than 400,000 tonnes.
The Sun has a concentration of 0.1 parts per billion (ppb) of beryllium. Beryllium has a concentration of 2 to 6 parts per million (ppm) in the Earth's crust and is the 47th-most abundant element. It is most concentrated (6 ppm) in the soils. Trace amounts of 9Be are found in the Earth's atmosphere. The concentration of beryllium in sea water is 0.2–0.6 parts per trillion. In stream water, however, beryllium is more abundant, with a concentration of 0.1 ppb.
Because of its low atomic number and very low absorption for X-rays, the oldest and still one of the most important applications of beryllium is in radiation windows for X-ray tubes. Extreme demands are placed on purity and cleanliness of beryllium to avoid artifacts in the X-ray images. Beryllium is used in X-ray windows because it is transparent to X-rays, allowing for clearer and more efficient imaging. Thin beryllium foils are used as radiation windows for X-ray detectors, and their extremely low absorption minimizes the heating effects caused by high-intensity, low energy X-rays typical of synchrotron radiation. Vacuum-tight windows and beam-tubes for radiation experiments on synchrotrons are manufactured exclusively from beryllium. In scientific setups for various X-ray emission studies (e.g., energy-dispersive X-ray spectroscopy) the sample holder is usually made of beryllium because its emitted X-rays have much lower energies (≈100 eV) than X-rays from most studied materials.
Low atomic number also makes beryllium relatively transparent to energetic particles. Therefore, it is used to build the beam pipe around the collision region in particle physics setups, such as all four main detector experiments at the Large Hadron Collider (ALICE, ATLAS, CMS, LHCb), the Tevatron and at SLAC. …
Natural beryllium is made up of solely the stable isotope beryllium-9. Beryllium is the only monoisotopic element with an even atomic number.
Beryllium-7 and beryllium-8 are key intermediates in stellar nucleosynthesis, but do not last long. It is believed that the beryllium in the universe was created in the interstellar medium when cosmic rays induced fission in heavier elements found in interstellar gas and dust, a process called cosmic ray spallation.
About one billionth (10−9) of the primordial atoms created in the Big Bang nucleosynthesis were 7Be. This is a consequence of the low density of matter when the temperature of the universe cooled enough for small nuclei to be stable. Creating such nuclei requires nuclear collisions that are rare at low density. Although 7Be is unstable and decays by electron capture into 7Li, with a half-life of 53.22 days under standard conditions, in the early universe the atoms were fully ionized and electron capture not significant. The conversion of 7Be to Li was only complete near the time of recombination.
The isotope 7Be is also a cosmogenic nuclide and shows an atmospheric abundance inversely proportional to solar activity. It decays exclusively by electron capture, and the 2s electrons of beryllium are the valence electrons responsible for chemical bonding. Therefore, when 7Be decays by L-electron capture, it does so by taking electrons from its atomic orbitals that may be participating in bonding. …
Approximately 35 micrograms of beryllium is found in the average human body, an amount not considered harmful. Beryllium is chemically similar to magnesium and therefore can displace it from enzymes, which causes them to malfunction. Because Be2+ is a highly charged and small ion, it can easily get into many tissues and cells, where it specifically targets cell nuclei, inhibiting many enzymes, including those used for synthesizing DNA. Its toxicity is exacerbated by the fact that the body has no means to control beryllium levels, and once inside the body, beryllium cannot be removed.
Chronic beryllium disease (CBD), or berylliosis, is a pulmonary and systemic granulomatous disease caused by inhalation of dust or fumes contaminated with beryllium; either large amounts over a short time or small amounts over a long time can lead to this ailment. Symptoms of the disease can take up to five years to develop; about a third of patients with it die and the survivors are left disabled. The International Agency for Research on Cancer (IARC) lists beryllium and beryllium compounds as Category 1 carcinogens.
In the US, the Occupational Safety and Health Administration (OSHA) has designated a permissible exposure limit (PEL) for beryllium and beryllium compounds of 0.2 μg/m3 as an 8-hour time-weighted average (TWA) and 2.0 μg/m3 as a short-term exposure limit over a sampling period of 15 minutes. …