The Halogens: What Textbooks Rarely Mention

(mostly adapted from Emsley, John. Nature’s Building Blocks.`Oxford. 2003 and from http://www.chemsoc.org

and http://www.lateralscience.co.uk)

Fluorine, F Fluorine, sometimes referred to as “Lucifer’s gas”, is so reactive that if steel wool would be exposed to it, it would burst into flames. (The oxidizing agent would be fluorine and not oxygen). Attempting to isolate the gas is a form of Russian roulette. Its discoverer, Henri Moissan, was poisoned several times, recovered but eventually died prematurely. Others such as Jerome Nickels and P. Louyet were not as “lucky” and were killed on the spot.

Some minerals release free fluorine which immediately reacts with water vapour in the air, forming hydrogen fluoride and ozone: 3 F_2(g) + 3 H₂O_(g) à 6 HF_(g) + O_3(g)

Chlorine, Cl This toxic oxidant was used during the first World War in Flanders where it took many lives or caused permanent lung damage in survivors. Of course in ionic form, chloride is an innocuous component of sodium chloride and it is involved in the transmission of nerve impulses.

Bromine, Br Although not as toxic as its simpler family members, bromine is still a strong oxidizing agent which causes burns or instant dermatitis upon contact. Even if experimented with in the snow ( I know I tried it!) it is still volatile and difficult to work with. As the picture reveals, it is the only liquid non-metallic element at room temperature.

Iodine, I If heated gently, this solid element sublimates; otherwise it melts first. It reacts with oils from the skin revealing fingerprints left on paper. Its vapour, which is created by the decomposition of NI₃, irritates the eyes and mucous membranes.

Astatine, At Every eight minutes, this element loses half of its nuclear identity. For this reason, none of the material originally prepared presently exists.