Chemistry · Ch 7 — The p-Block Elements
Physical Properties
Physical Properties
Physical Properties
The halogens show textbook-smooth trends in their physical behaviour. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid — and both melting and boiling points climb steadily as atomic number increases down the group.
All of the common halogens are strikingly coloured, because their outer electrons absorb specific quanta of radiation in the visible region and jump to a higher energy level; the exact colour seen depends on which wavelengths get absorbed:
- — yellow
- — greenish yellow
- — red
- — violet
Fluorine and chlorine actually react with water rather than simply dissolving in it. Bromine and iodine, by contrast, are only sparingly soluble in water but dissolve well in non-aqueous media — chloroform, carbon tetrachloride, carbon disulphide and assorted hydrocarbons chief among them, giving brightly coloured solutions. …