1817

Selenium

• Jöns Jacob Berzelius and Johan Gottlieb Gahn
• owned a chemical plant that produced sulfuric acid
• by the “lead chamber” process.
• Berzelius was professor in chemistry and pharmacy
• at the Karolinska Institute in Stockholm.
• Gahn was chemist for the Swedish Board of Mines.
• They found a red precipitate in the lead chambers
• that burned with a smell like horseradish.
• It was like tellurium, named for the Earth,
• so they named it selenium for the Moon.

Atomic number 34

• Selenium is sensitive to light;
• its electric resistance decreases
• when a light shines on it.
• Therefore, selenium is used
• in light meters, photocopiers,
• photocells, solar cells, and as a toner
• for developing black and white photographs.

Stuff with colors

• Powdered amorphous selenium
• is brick red.
• Rapidly melted into beads,
• it’s black.
• Its most stable and dense allotrope,
• forming hexagonal structures,
• is gray.
• Selenium dioxide polymer
• is yellow.
• A little selenium is good for you,
• even necessary,
• but too much is a horse
• of another color.