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Selenium

/səˈliːniəm/noun

A nonmetal element, number 34, used in glassmaking and photocells and needed in the diet in trace amounts.

The Greek roots

σελήνη
selḗnē
moon

Literally: moon-metal

Follow a root:σελήνη5 words

The story of the word

Berzelius found it in 1817 in the red sludge at the bottom of a sulphuric acid works and took it at first for tellurium. When it proved to be new he named it after the moon, because tellurium had been named after the earth and the two kept company. Its electrical resistance drops when light falls on it, which made the selenium cell the eye of early fax machines and light meters.

How it travelled
Ancient Greek → scientific coinage → English
First recorded
1818

Same family

Seleneseleniteselenology

In a sentence

Two Brazil nuts a day supply more selenium than most people need.

Built on the same root

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