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Thursday, June 16, 2016

Beryllium chemical element

Beryllium was discovered in 1798 by the french Louis-Nicolas Vauquelin.
The chemical symbol for Beryllium is Be and its atomic number is 4.
We find it listed in the periodic table of elements in group 2 and period 2 and block s.
Beryllium belongs to the family or series of chemical alkaline earth metals such as for example Barium, Calcium, Magnesium, ...This element is stable, Beryllium came from the latin word berullos which means Green.


Beryllium chemical element



Atomic number (Z) 4
Group, block group 2 (alkaline earth metals), s-block
Period: period 2
Element category: alkaline earth metal
Standard atomic weight (±) (Ar): 9.0121831(5)[1]
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 m.p. 1.690 g/cm3
Critical point: 5205 K,  MPa (extrapolated)
Heat of fusion: 12.2 kJ/mol
Heat of vaporization: 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
Ionization energies:1st: 899.5 kJ/mol
2nd: 1757.1 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.
Speed of sound thin rod: 12,890 m/s (at r.t.)[3]
Thermal expansion: 11.3 µm/(m•K) (at 25 °C)
Thermal conductivity: 200 W/(m•K)
Electrical resistivity: 36 nΩ•m (at 20 °C)