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Beryllium,  4Be
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
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)
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
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
Discovery Louis Nicolas Vauquelin (1798)
First isolation Friedrich Wöhler & Antoine Bussy (1828)
· references

Beryllium is the chemical element with the symbol Be and atomic number 4.



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.


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.


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 at both ends, which is usually colored in pink or white, right above the brass mesh gasket and the other near the contacts. However, extracting the metal from the oxide is very dangerous, as beryllium compounds are more toxic than the metal, due to being soluble.


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.


  • Synthetic gemstones
  • X-ray window
  • Element collecting



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.


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.


Best to try to recycle it.


Relevant Sciencemadness threads