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Also known as Se, element 34, 34Se

Selenium is a chemical element; it has symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust. Selenium (from ) was discovered in 1817 by , who noted the similarity of the new element to the previously discovered tellurium (named for the Earth).

OverviewAI-generated

Selenium is a chemical element with the symbol Se and atomic number 34. Its standard chemical formula is Se, and it has a mass of 78.971. The element was discovered in 1817. It exhibits oxidation states of -2, 1, 2, and 4, and has an electronegativity of 2.55. The ionic radius is 0.50.

Physical properties include a density of 4.28, a melting point of 392, and a boiling point of 1265. The vapor pressure is 0. Safety guidelines list a time-weighted average exposure limit of 0.2 and an immediately dangerous to life or health value of 1. The NIOSH Pocket Guide ID is 0550. In digital text, it is represented by the Unicode character "硒".

Synthesized by Vinony from 31 facts across 4 sources: Wikidata, PubChem, PubMed, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.