Difference between revisions of "Beryllium"
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Beryllium can be found in beryllium copper/bronze tools, in concentrations between 0.5—3%. Extraction is a complex process and may not worth the effort, especially due to the low concentration of Be. | Beryllium can be found in beryllium copper/bronze tools, in concentrations between 0.5—3%. Extraction is a complex process and may not worth the effort, especially due to the low concentration of Be. | ||
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| + | Cavity magnetrons used in microwave ovens have a [[beryllium oxide]] insulator, which is usually colored in pink or white, right above the brass mesh ring. However, extracting the metal from the oxide is very dangerous, as beryllium compounds are more toxic than the metal, due to being soluble. | ||
==Preparation== | ==Preparation== | ||
Revision as of 13:13, 17 March 2018
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Beryllium, Be | ||||
| Appearance | Silvery-white | ||||
| Beryllium in the periodic table | |||||
| |||||
| Atomic number | 4 | ||||
| Standard atomic weight (Ar) | 9.0121831(5) | ||||
| Group, block | (alkaline earth metals); s-block | ||||
| Period | period 2 | ||||
| Electron configuration | [He] 2s2 | ||||
per shell | 2, 2 | ||||
| Physical properties | |||||
| Silvery-white | |||||
| Phase | Solid | ||||
| Melting point | 1560 K (1287 °C, 2349 °F) | ||||
| Boiling point | 2742 K (2469 °C, 4476 °F) | ||||
| Density near r.t. | 1.85 g/cm3 | ||||
| when liquid, at | 1.69 g/cm3 | ||||
| Critical point | 5205 K, MPa | ||||
| Heat of fusion | 12.2 kJ/mol | ||||
| Heat of | 292 kJ/mol | ||||
| Molar heat capacity | 16.443 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | +2, +1 (an amphoteric oxide) | ||||
| Electronegativity | Pauling scale: 1.57 | ||||
| energies |
1st: 899.5 kJ/mol 2nd: 1,757.1 kJ/mol 3rd: 14,848.7 kJ/mol | ||||
| Atomic radius | empirical: 112 pm | ||||
| Covalent radius | 96±3 pm | ||||
| Van der Waals radius | 153 pm | ||||
| Miscellanea | |||||
| Crystal structure | Hexagonal close-packed (hcp) | ||||
| Speed of sound thin rod | 12,890 m/s (at 20 °C) | ||||
| Thermal expansion | 11.3 µm/(m·K) (at 25 °C) | ||||
| Thermal conductivity | 200 W/(m·K) | ||||
| Electrical resistivity | 36·10-9 Ω·m | ||||
| Magnetic ordering | Diamagnetic | ||||
| Young's modulus | 287 GPa | ||||
| Shear modulus | 132 GPa | ||||
| Bulk modulus | 130 GPa | ||||
| Poisson ratio | 0.032 | ||||
| Mohs hardness | 5.5 | ||||
| Vickers hardness | 1670 MPa | ||||
| Brinell hardness | 590–1320 MPa | ||||
| CAS Registry Number | 7440-41-7 | ||||
| History | |||||
| Discovery | Louis Nicolas Vauquelin (1798) | ||||
| First isolation | Friedrich Wöhler & Antoine Bussy (1828) | ||||
Beryllium is the chemical element with the symbol Be and atomic number 4.
Contents
Properties
Chemical
Beryllium is more chemically similar to aluminium than its close neighbors in the periodic table, due to having a similar charge-to-radius ratio. A protective oxide layer forms around beryllium that prevents further reactions with air unless heated above 1000 °C. It will dissolve in alkali solutions and non-oxidizing acids, such as hydrochloric acid releasing hydrogen gas, but not in nitric acid, as it forms a protective oxide layer, similar to aluminium. It will also dissolve in alkali solutions.
Like aluminium halides, beryllium halides tend to be covalent due to the small atomic radius and high charge density.
Physical
Beryllium is a white-gray and hard metal, brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional stiffness (Young's modulus 287 GPa) and a reasonably high melting point. Beryllium has high specific heat (1925 J·kg−1·K−1) and thermal conductivity (216 W·m−1·K−1), which make beryllium the metal with the best heat dissipation characteristics per unit weight. Beryllium has the fastest speed of sound in any known metal, with a value of 12.9 km/s at standard conditions.
Availability
Beryllium samples can be bought online from Metallium, in ampoules (recommended) or pellets and rods.
Beryllium can be found in beryllium copper/bronze tools, in concentrations between 0.5—3%. Extraction is a complex process and may not worth the effort, especially due to the low concentration of Be.
Cavity magnetrons used in microwave ovens have a beryllium oxide insulator, which is usually colored in pink or white, right above the brass mesh ring. However, extracting the metal from the oxide is very dangerous, as beryllium compounds are more toxic than the metal, due to being soluble.
Preparation
Beryllium metal can be prepared by reducing beryllium chloride with potassium metal, in an inert atmosphere:
- BeCl2 + 2 K → 2 KCl + Be
It can also be prepared from the electrolysis of a mixture of molten beryllium fluoride and sodium fluoride.
Projects
- Synthetic gemstones
- X-ray window
- Element collecting
Handling
Safety
Although beryllium and beryllium compounds have interesting properties worth studying, both are extremely toxic, and inhaling their dust can result in a serious medical condition called "berylliosis". The International Agency for Research on Cancer (IARC) lists beryllium and beryllium compounds as Category 1 carcinogens.
Storage
Bulk beryllium metal should be kept away from strong acids or sharp objects. Powdered beryllium must be kept in closed containers, away from any draft.
Disposal
Best to try to recycle it.
