Selenium - ASCII Periodic Table of the Elements

ASCII PERIODIC TABLE OF THE ELEMENTS

  Se

Relative atomic mass: 78.96 ± 0.03

English: Selenium
French: Sélénium
Croatian: Selenij
German: Selen
Italian: Selenio
Spanish: Selenio

Atomic number: 34
Group numbers: 16
Period: 4
Standard state (20 °C): solid

Discovery: 1817 Jöns Jacob Berzelius (SE)

Selenium was discovered by Jöns Jacob Berzelius (SE) in 1817. The origin of the name comes from the Greek word 'selene' meaning 'moon'. It is a soft metalloid similar to sulfur, unaffected by water and soluble in alkalis and nitric acid. The colour ranges from grey metallic to red glassy. Selenium burns in air and is toxic by inhalation or ingestion. Also it conducts electricity when struck by light. Selenium is obtained from lead, copper and nickel refining. Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers, also colours glass red.

Electronic configuration: [Ar] 3d¹⁰ 4s² 4p⁴
Formal oxidation number: -2 +4 +6
Atomic radius: 116 pm

Electronegativities: 2.55
Thermal conductivity: 2.04 W/(m K)
Electrical resistivity (20 °C): 12 μΩcm

Melting point: 221 °C
Boiling point: 685 °C

Heat of fusion: 5.1 kJ/mol
Heat of vaporization: 90 kJ/mol
Heat of atomization: 226.4 kJ/mol