Beryllium (revised)
BERYLLIUM (REVISED)
Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.
Overview
Beryllium is the lightest member of the alkaline earth metals family. These metals make up Group 2 (IIA) of the periodic table. They include beryllium, magnesium, calcium, strontium, barium, and radium. Elements in the same column of the periodic table have similar chemical properties. The periodic table is a chart that shows how the chemical elements are related to each other.
Beryllium was discovered by French chemist Louis-Nicolas Vauquelin (1763-1829) in 1798. Vauquelin suggested the name glucinium, meaning "sweet tasting," for the element because the element and some of its compounds have a sweet taste. The name beryllium was adopted officially in 1957.
Beryllium-copper alloys account for about three-quarters of all the beryllium produced. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals.
SYMBOL
Be
ATOMIC NUMBER
4
ATOMIC MASS
9.012182
FAMILY
Group 2 (IIA)
Alkaline earth metal
PRONUNCIATION
buh-RIL-Lee-um
Discovery and naming
A common compound of beryllium, beryl, was known in ancient Egypt, but nothing was known about the chemical composition of this mineral until the end of the eighteenth century. In 1797, French mineralogist René-Just Haüy (1743-1822) completed studies on beryl and emerald. Emerald is a naturally occurring green gemstone. Haüy was convinced that these two minerals were nearly identical. He asked a friend, Vauquelin, to determine the chemical composition of the two minerals.
When Vauquelin performed his chemical analysis, he found a new material that had been overlooked because it is so much like aluminum. His data proved that the material was not aluminum. He suggested calling the new element glucinium. Scientists referred to the element by two different names, beryllium and glucinium, for 160 years. The name beryllium comes from the mineral, beryl, in which it was first discovered.
Physical properties
Beryllium is a hard, brittle metal with a grayish-white surface. It is the least dense (lightest) metal that can be used in construction. Its melting point is 1,287°C (2,349°F) and its boiling point is estimated to be about 2,500°C (4,500°F). Its density is 1.8 grams per cubic centimeter. The metal has a high heat capacity (it can store heat) and heat conductivity (it can transfer heat efficiently).
Interestingly, beryllium is transparent to X rays. X rays pass through the metal without being absorbed. For this reason, beryllium is sometimes used to make the windows for X-ray machines.
Chemical properties
Beryllium reacts with acids and with water to form hydrogen gas. It reacts briefly with oxygen in the air to form beryllium oxide (BeO). The beryllium oxide forms a thin skin on the surface of the metal that prevents the metal from reacting further with oxygen.
Occurrence in nature
Beryllium never occurs as a free element, only as a compound. The most common ore of beryllium is beryl. Beryl has the chemical formula Be3(Al2(SiO3))6.
The original name of beryllium—glucinium—meant "sweet tasting," since the element and some of its compounds have a sweet taste.
The major beryl producer in the world is the United States. The only mine currently producing beryl is in Delta, Utah. Beryl is also converted to beryllium and its compounds in plants in Delta; Elmore, Ohio; and near Reading, Pennsylvania. Beryl is also obtained from mines in China, Russia, and Brazil.
Beryllium is relatively common in the Earth's crust. Its abundance is estimated at 2 to 10 parts per million.
Isotopes
Only one naturally occurring isotope of beryllium exists, beryllium-9. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope.
Six radioactive isotopes of beryllium are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive.
None of the isotopes of beryllium has any commercial use.
Extraction
Beryllium ores are first converted to beryllium oxide (BeO) or beryllium hydroxide (Be(OH)2). These compounds are then converted to beryllium chloride (BeCl2) or beryllium fluoride (BeF2). Finally, the pure metal is isolated by: (1) an electric current:
or, (2) reaction with magnesium metal at high temperature:
Uses
By far the greatest use of beryllium metal is in alloys. Beryllium alloys are popular because they are tough, stiff, and lighter than similar alloys. For example, a new alloy of beryllium and aluminum called Beralcast was released in 1996. Beralcast is 3 times as stiff and 25 percent lighter than pure aluminum. The maker of Beralcast expects sales of $20 million from its use in helicopters and satellite guidance systems.
The most popular alloys of beryllium at the present time are those with copper metal. Copper-beryllium alloys contain about 2 percent beryllium. They conduct heat and electricity almost as well as pure copper but are stronger, harder, and more resistant to fatigue (wearing out) and corrosion (rusting). These alloys are used in circuit boards, radar, computers, home appliances, aerospace applications, automatic systems in factories, automobiles, aircraft landing systems, oil and gas drilling equipment, and heavy machinery.
Compounds
Fifteen percent of the beryllium used in the United States is in the form of beryllium oxide (BeO). It is a white powder that can be made into many different shapes. It is desirable as an electrical insulator because it conducts heat well, but an electrical current poorly. It is used in high-speed computers, auto ignition systems, lasers, microwave ovens, and systems designed to hide from radar signals.
Health effects
Beryllium is a very toxic metal. It is especially dangerous in powder form. The effects of inhaling beryllium powder can be acute or chronic. Acute effects are those that occur very quickly as the result of large exposures. Chronic effects are those that occur over very long periods of time as the result of much smaller exposures. Acute effects of inhaling beryllium powder include pneumonia-like symptoms that can result in death in a short time. Chronic effects include diseases of the respiratory system (throat and lungs), such as bronchitis and lung cancer.
How impurity leads to beauty
P urity is not always desirable, at least not for gemstones. A gemstone is a mineral that can be cut and polished for use in jewelry. Some typical gemstones are jade, sapphire, diamond, ruby, amethyst, emerald, spinel, moonstone, topaz, aquamarine, opal, and turquoise. Gemstones are often used as birthstones, which honor the month in which a person is born. (For instance, the birthstone for April is a diamond.)
Gemstones are valued for their beautiful colors and crystal forms. Light reflects off them in brilliant patterns. The crystal forms are the result of very exact arrangements of atoms in the gemstone. Its perfection contributes to its beauty and its monetary value.
But gemstone color is due to very small impurities in the mineral. For example, the mineral known as corundum is colorless when pure. But a very small amount of chromium produces a bright red color. The corundum is now a ruby. A touch of iron or titanium produces shades of yellow, green, purple, pink, or blue that turn it into a sapphire.
Two gemstones are made primarily of beryl. They are emeralds and aquamarines. In emeralds, traces of chromium produce a brilliant green color. In aquamarines, iron is the impurity. It gives the beryl a beautiful blue color.
These effects can be avoided fairly easy. Workers can wear masks over their faces to filter out beryllium particles. Filtering devices in factories where beryllium is used also prevent beryllium from getting into the air.
Beryllium
Beryllium
melting point: 1,285°C
boiling point: 2,500°C
density: 1.848 g/cm3
most common ions: Be2+
Beryllium was identified as a unique element and as a constituent of the mineral beryl and the gem emerald by the French chemist Louis Vauquelin in 1797. Metallic beryllium was isolated in 1828 by the scientists (working independently of one another) Antoine Bussy and Friedrich Wöhler. Beryllium usage was not common until a 1920s discovery that the 2 percent addition of beryllium to copper resulted in an alloy six times stronger than the original material. Beryllium has a melting point of 1,285°C (2,345°F), a boiling point of 2,500°C (4,532°F), and a density of 1.848 g/cm3. Its most common oxidation state is +2. It has a high heat adsorption capacity and is nonmagnetic and corrosion-resistant.
Beryllium is one of the most toxic elements in the Periodic Table. It is the agent responsible for chronic beryllium disease (CBD), an often-fatal lung disease, and is a Class A carcinogen (as determined by the U.S. Environmental Protection Agency). The primary route of human exposure to beryllium and beryllium compounds is inhalation.
Approximately fifty beryllium minerals occur in nature and over half of these minerals are silicates. Beryllium is mined primarily from these silicates, including beryl, Al2Be3Si6O18, 5 percent (wt.) beryllium, and bertrandite, Be4(OH)2Si2O7, 15 percent (wt.) beryllium. The world resources of beryllium are estimated at approximately 80,000 tons. Other common beryllium silicates include chrysoberyl, BeAl2O4, and phenacite, Be2SiO4.
Beryllium is a key component of materials used in the aerospace, electronics, aviation, telecommunications, automotive, and nuclear power
industries. It is used in aircraft bearings and bushings; fuel containers for solid propulsion jet and rocket fuel systems; gyros, reentry vehicles, springs, switches, and relays and connectors in electronic systems; fiber optics and cellular network communication systems; optical laser scanners; automobile air bag sensors, ignition switches, and power steering systems; and to moderate nuclear reactions in power plants. Beryllium oxide ceramics have a thermal conductivity second only to that of diamond among electrically insulating materials, dissipating nearly 300 watts/millikelvin (W/mK) at room temperature.
see also Toxicity; WÖhler, Friedrich.
Tammy P. Taylor
Nancy N. Sauer
Bibliography
Hampel, Clifford A., and Hawley, Gessner G., eds. (1973). The Encyclopedia of Chemistry, 3rd edition. New York: Van Nostrand Reinhold.
Proctor, Nick H., and Hughes, James P., eds. (1978). Chemical Hazards of the Workplace. Philadelphia: Lippincott.
Taylor, T. P.; Ding, M.; Ehler, D. S.; Foreman, T. M.; Kaszuba, J. P.; and Sauer, N. N. (2003). "Beryllium in the Environment: A Review." Journal of Environmental Science and Health A38(2):439–469.
beryllium
beryllium
be·ryl·li·um / bəˈrilēəm/ • n. the chemical element of atomic number 4, a hard gray metal. (Symbol: Be)