Archive | Halogens


    At any given time, there is only 25 g of Astatine on Earth.  This element is so rare that very little is known about its chemistry.  Thus, the question mark! next element                             previous element


Crystals of solid iodine have a deep purple color.   next element                                         previous element


  Bromine, in the form of HOBr, is sometimes added to pools in place of chlorine (in the form of HOCl).  HOCl and HOBr are effective antiobacterial agents.  At high temperatures, HOBr and HOCl can be removed from pool water due to the following reactions: HOCl (aq) + HCl (aq) –> H2O (g) + Cl2 […]


Chlorine, often in the form of calcium hypochlorite, Ca(OCl)2, is added to swimming pools to kill microorganisms.  The acidic form of hypochlorite, hypochlorous acid (HOCl), is the effective antibiotic: OCl– + H3O+ –> HOCl + H2O This means that pool water must be kept acidic enough to allow HOCl to form, but not too acidic (you don’t […]


When a fluorine atom gains an electron, it becomes a fluoride ion: F + electron –> F– Teeth are often treated with fluoride.  This is because when fluoride substitutes for hydroxide in hydroxyapatite (the mineral in teeth), a stronger mineral results: Ca10(PO4)6(OH)2 + 2 F– –> Ca10(PO4)6(F)2 + 2 OH– next element           […]