Selenium: the essentials


Selenium: historical information

Selenium was discovered by Jöns Berzelius in 1817 at Sweden. Origin of name: from the Greek word "selene" meaning "moon".


Selenium around us Read more »

Selenium is essential to mammals and higher plants, but only in small amounts. Selenium is said to stimulate the metabolism. It may help protest against free radical oxidants and against some heavy metals. Livestock grown in areas containing high amounts of selenium in the soil and in which a plant called Astragalus ("loco weed" in USA) is present are poisoned. This is because Astragalus concentrates selenium. On the other hand, sheep grown in areas containing deficient amounts of selenium in the soil develop "white muscle disease".


Abundances for selenium in a number of different environments. More abundance data »
Location ppb by weight ppb by atoms Links
Universe 30 0.5 Chemical elements abundance by weight in the universe on a miniature periodic table spark table
Crustal rocks 50 10 Chemical elements abundance by weight in the earth's crust on a miniature periodic table spark table

Physical properties Read more »

Heat properties Read more »

Crystal structure Read more »

The solid state structure of selenium is: monoclinic.

Selenium: orbital properties Read more »

Selenium atoms have 34 electrons and the shell structure is The ground state electronic configuration of neutral Selenium is [Ar].3d10.4s2.4p4 and the term symbol of Selenium is 3P2.



Cu2Se + Na2CO3 + 2O2 → 2CuO + Na2SeO3 + CO2


H2SeO3 + 2SO2 + H2O → Se + 2H2SO4

Selenium isotopes Read more »


Table. Stables isotopes of selenium.
Isotope Mass
(atom %)
spin (I)
moment (μ/μN)
74Se 73.9224746 (16) 0.89 (4) 0
76Se 75.9192120 (16) 9.37 (29) 0
78Se 77.9173076 (16) 23.77 (28) 0
80Se 79.9165196 (19) 49.61 (41) 0
82Se 81.9166978 (23) 8.73 (22) 0

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