Beryllium (Be)

Stable Isotopes of Beryllium

Isotope Z(p) N(n) Atomic Mass Natural Abundance Nuclear Spin
Be-9 4 5 9.0121822 100.00% 3/2-



Beryllium was discovered in 1797 by Louis-Nicolas Vauquelin. Its name derives from the Greek word beryllos, meaning "beryl."  

The lightest alkaline-earth metallic element, beryllium is a hard, brittle, gray-white metal, with a hexagonal close-packed crystal system. It is the lightest structural metal known and can be fabricated by rolling, forging or machining. It is soluble in acids (except nitric acid) and alkalis. It is resistant to oxidation at ordinary temperatures, with high heat capacity and thermal conductivity. Its chemical reactions are similar to those of aluminum.

Beryllium is permeable to x-rays. It occurs in several minerals, mostly combined with silica and alumina, the most common minerals being beryl, chrysoberyl, phenacite and bertrandite. Beryllium oxide is a component of precious stones, such as emerald, aquamarine and topaz. It is found in trace amounts in the ore feldspar. It is used in nuclear reactors to moderate the velocity of slow neutrons.

Elemental beryllium and its compounds are very poisonous by inhalation or intravenous route. Chronic inhalation of beryllium dusts or fumes can cause berylliosis, a serious lung disease. Skin contact with soluble salts of the metal can cause dermatitis. Beryllium also is a carcinogen: there is sufficient evidence of its inducing cancer in animals and humans. It is one of the United States Environmental Protection Agency's listed priority pollutant metals in the environment.

Properties of Beryllium

Name Beryllium
Symbol Be
Atomic number 4
Atomic weight 9.01218
Standard state Solid at 298 °K
CAS Registry ID 7440-41-7
Group in periodic table 2
Group name Alkaline earth metal
Period in periodic table 2
Block in periodic table s-block
Color Gray-white or lead gray
Classification Metallic 
Melting point 1287 °C
Boiling point 2970 °C
Thermal conductivity 190 W/(m·K)
Electrical resistivity 3.36 x 10-10 µΩ·cm at 20 °C
Electronegativity 1.5
Specific heat 1820 J/(kg·K)
Heat of vaporization 297 kJ·mol-1
Heat of fusion 7.95 kJ·mol-1
Density of solid 1.85 g/cm3
Electron configuration  [He]2s2 
Oxidation state  2+ 
Atomic radius  1.06 Å 
Ionic radius  Be2+ : 0.30 Å

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