Definition: A heavy metal is a toxic metal. There is no standard definition assigning metals as heavy metals. Some lighter metals and metalloids are toxic and thus are termed heavy metals, which some heavy metals, such as gold, typically are not toxic. Most heavy metals have a high atomic number, atomic weight and a specific gravity greater than 5.0 Heavy metals include some metalloids, transition metals, basic metals, lanthanides and actinides.
Alternate Spellings: heavy metals
Examples of heavy metals include lead, mercury, cadmium, sometimes chromium. Less commonly, metals including iron, copper, zinc, aluminum, beryllium, cobalt, manganese and arsenic may be considered heavy metals.