Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon).
Their locations can vary depending on the molecule they are associated with but they are usually in a "cloud " that is on the outside of an atom/molecule and if the atom is unstable the electrons tend to be located farther away from the atom.
iron Presence of trace elements, irradiation and iron impurities give the gem amethyst its purplish color!
