<unk>  is a chemical element with the symbol<unk>  (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials.<unk>  is soft and malleable, and also has a relatively low melting point. When freshly cut,<unk>  is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air.<unk>  has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.<unk>  is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature;<unk>  and<unk>  oxides react with acids and bases, and it tends to form covalent bonds. Compounds of<unk>  are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the group,<unk>  tends to bond with itself; it can form chains and polyhedral structures. Since<unk>  is easily extracted from its ores, prehistoric people in the Near East were aware of it. Galena is a principal ore of<unk>  which often bears silver. Interest in silver helped initiate widespread extraction and use of<unk>  in ancient Rome.<unk>  production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution.<unk>  played a crucial role in the development of the printing press, as movable type could be relatively easily cast from<unk>  alloys. In 2014, the annual global production of<unk>  was about ten million tonnes, over half of which was from recycling.<unk> 's high density, low melting point, ductility and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, plumbing, batteries, bullets and shot, weights, solders, pewters, fusible alloys, white paints,<unk> ed gasoline, and radiation shielding. In the late 19th century,<unk> 's toxicity became recognized widely, although a number of well-educated ancient Greek and Roman writers were aware of this fact and even knew some of the symptoms of<unk>  poisoning.<unk>  is a neurotoxin that accumulates in soft tissues and bones; it damages the nervous system and interferes with the function of biological enzymes, causing neurological disorders ranging from behavioral problems to brain damage, and also affects general health, cardiovascular, and renal systems.
Lead
Basilicon
Mercury
Arsenic
Metaldehyde
Sybil 
Vinyl chloride
Lindane