Chemical reactions of the elements

Reaction of selenium with air

Selenium burns in air to form the solid dioxide selenium(IV) oxide, SeO2.

Se8(s) + 8O2(g) → 8SeO2(s)

Reaction of selenium with water

Reaction of selenium with the halogens

Selenium reacts with fluorine, F2, and burns to form the hexafluoride selenium(VI) fluoride.

Se8(s) + 24F2(g) → 8SeF6(l) [orange]

Selenium (preferably suspended in CS2) reacts with chlorine and bromine to form diselenium dichloride, Se2Cl2 and diselenium dibromide, Se2Br2 respectively.

Se8 + 4Cl2 → 4Se2Cl2(l) [orange]

Se8 + 4Br2 → 4Se2Br2(l) [orange]

Carefully done, selenium reacts with fluorine, F2, at 0°C to form the tetrafluoride selenium(IV) fluoride. Selenium also reacts under controlled conditions with the other halogens chlorine, Cl2, bromine, Br2, and iodine, I2, to form the respective tetrahalides selenium(IV) chlrode, selenium(IV) bromide, and selenium(IV) iodide.

Se8(s) + 16F2(g) → 8SeF4(s) [colourless]

Se8(s) + 16Cl2(g) → 8SeCl4(s)

Se8(s) + 16Br2(g) → 8SeBr4(s)

Se8(s) + 16I2(g) → 8SeI4(s)

Reaction of selenium with acids

Selenium does not react with dilute non-oxidizing acids.

Reaction of selenium with bases

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selenium atomic number