We Use Cookies
We use cookies and other tracking technologies to improve your browsing experience on our website, to show you personalized content and targeted ads, to analyze our website traffic, and to understand where our visitors are coming from. For more information, please review our cookie policy and privacy policy.
By choosing I Accept, you consent to our use of cookies and other tracking technologies.

Selenium (Se)

From Wikipedia, the free encyclopediaSelenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.

Selenium in the periodic table

Atomic number34
Element categoryNonmetal

Physical properties

Phase at STPSolid
Density4.81 g/cm3
Atomic weight78.9718 u
Melting point494 K
220.85 °C
429.53 °F
Boiling point958 K
684.85 °C
1264.73 °F

Atomic properties

Electronegativity (Pauling Scale)2.55
Electron affinity194.959 kJ/mol
Oxidation states−2, −1, +1, +2, +3, +4, +5, +6
(a strongly acidic oxide)
Ionization energies
1941 kJ/mol
2 2045 kJ/mol
3 2973.7 kJ/mol
4 4144 kJ/mol
5 6590 kJ/mol
6 7880 kJ/mol
7 14990 kJ/mol

Electron configuration

Elektronkonfiguration (shorthand)[Ar] 3d10 4s2 4p4
Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4
Electrons per shell2, 8, 18, 6


Discovered byJöns Jakob Berzelius
Johan Gottlieb Gahn
Warning: Undefined variable $footer in /customers/a/d/1/periodictable.one/httpd.www/inc/footer.php on line 34