Beryllium
Beryllium is a metallic element, with atomic number 4 and atomic weight 9. The metal is hard, silvery-white in color, and very light – less than twice as dense as water, and only two-thirds as dense as aluminum, which it somewhat resembles. Beryllium has a very high melting point at 2,349°F (1287°C). The combination of its light weight and high melting point make it valuable for making metal alloys.
Because of the toxic nature of beryllium, careful control over the quantity of dust and fumes in the workplace must be maintained.
Contents
Name
| Previous Element: Lithium Next Element: Boron |
| |
| Physical Properties | ||
|---|---|---|
| Color | Steel gray | |
| Phase at Room Temp. | solid | |
| Density (g/cm3) | 1.848 | |
| Hardness (Mohs) | --- | |
|
Melting Point (K) |
1551.2 | |
|
Boiling Point (K) |
2773 | |
| Heat of Fusion (kJ/mol) | 9.8 | |
| Heat of Vaporization (kJ/mol) | 309 | |
| Heat of Atomization (kJ/mol) | 324 | |
| Thermal Conductivity (J/m sec K) | 201 | |
| Electrical Conductivity (1/mohm cm) | 250 | |
| Source | Beryl (silicate) | |
| Atomic Properties | ||
| Electron Configuration | [He]2s2 | |
|
Number of Isotopes |
1 | |
| Electron Affinity (kJ/mol) | -241 | |
| First Ionization Energy (kJ/mol) | 899.4 | |
| Second Ionization Energy (kJ/mol) | 1757.1 | |
| Third Ionization Energy (kJ/mol) | 14848.3 | |
| Electronegativity | 1.57 | |
| Polarizability (Å3) | 5.6 | |
| Atomic Weight | 9.012182 | |
| Atomic Volume (cm3/mol) | 4.9 | |
| Ionic Radius2- (pm) | --- | |
| Ionic Radius1- (pm) | --- | |
| Atomic Radius (pm) | 112 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | 59 | |
| Ionic Radius3+ (pm) | --- | |
| Common Oxidation Numbers | +2 | |
| Other Oxid. Numbers | --- | |
| Abundance | ||
| In Earth's Crust (mg/kg) | 2.8 | |
| In Earth's Ocean (mg/L) | 5.6×10-6 | |
| In Human Body (%) | near 0% | |
| Regulatory / Health | ||
| CAS Number | 7440-41-7 | |
| OSHA Permissible Exposure Limit (PEL) | TWA: 0.002 mg/m 3 Ceiling: 0.005 mg/m 3 | |
| OSHA PEL Vacated 1989 | TWA: 0.002 mg/m3 Ceiling: 0.005 mg/m3 | |
|
NIOSH Recommended Exposure Limit (REL) |
IDLH: 4 mg/m3 | |
|
Sources: |
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Beryllium was not known to ancient or medieval civilizations, and was first recognized by the French scientist, Nicholas Louis Vauquelin in 1798. He discovered it as a component of the mineral beryl, and named it beryllium. Metallic beryllium was not isolated until 1828, by Friederich Wohler in Germany.
Sources
The most common mineral containing beryllium is beryl, a silicate mineral with the chemical formula Be3Al2Si6O18. Beryl forms distinctive hexagonal prisms, and is found in the igneous rock granite and special igneous rocks, derived from granites, known as pegmatites. Colored, transparent varieties of beryl may be gems, such as emerald (green), aquamarine (blue-green), heliodor (yellow), and morganite (pink). In addition to being found in beryl, beryllium is found in the mineral bertrandite Be4Si2O7(OH)2, which in recent years has become a major ore of this element, in addition to beryl. Bertrandite is found in certain volcanic rocks derived from granite.
Bertrandite ore mined in Utah makes up nearly all of U.S. production, which is about two-thirds of the world supply. Russia produces most of the rest, from beryl ores. Five to ten other countries mine small amounts of beryl. The United States produces and exports large amounts of beryllium alloys and compounds, and thus is a net importer of ores, but a net exporter of finished beryllium products.
Small amounts of beryllium become available from recycling of beryllium-containing scrap.
Uses
Most beryllium is used in metal alloys, which account for more than 70% of world consumption. Because beryllium is very light and has a high melting temperature, it is an ideal metal for use in the aerospace and defense industry, almost always alloyed with other metals. Beryllium metal also has the interesting characteristic of being elastic. Consequently, it is used in the manufacture of springs, gears and other machine components that need a degree of elasticity. Another everyday application is in the manufacture of gasoline pumps, because an alloy of copper and beryllium (beryllium bronze) does not spark when hit against other metals, nor emit sparks from static electricity.
Rods made of beryllium metal and oxide are used to control nuclear reactions, because beryllium absorbs neutrons better than any other metal.
Most organisms do not depend on beryllium for growth. In fact, beryllium dust and fumes can be dangerous to human health when inhaled. Consequently, the Clean Air Act demands very careful handling of beryllium dust and fumes to minimize or eliminate its danger to humans.
Substitutes and Alternative Sources
In some applications, graphite, steel and titanium can be used in place of beryllium. However, it is a critical component of many military and aerospace applications, and even though it is expensive to produce (costing more than silver), it is not often replaced by other materials.
Further Reading
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
