Selenium
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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 s
Se Black Red
Structure of hexagonal (gray) selenium
Selenium is named after Selene, the Greek Goddess of the Moon
Native selenium in sandstone, from a uranium mine near Grants, New Mexico
Arsenic
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Arsenic is a chemical element; it has the symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and a
Selenium
…with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. Selenium forms two oxides: selenium dioxide (SeO2) and selenium trioxide (SeO3). Selenium dioxide is formed by combustion of elemental selenium…
Arsen 1a
Gray arsenic nodule
A large sample of native arsenic from Sainte-Marie-aux-Mines, France
Realgar