Mercury (element)
Mercury may be seen as a transition metal, but it is normally seen as a post-transition metal. It is in Group 12 of the periodic table. Mercury has seven stable (nonradioactive) isotopes. 202Hg is the most common isotope. Mercury makes a blue to ultraviolet color in a tube when a spark is passed through it. The ultraviolet light can kill germs or light fluorescent lamps.