The chemical element Lead (Latin: Plumbum) with chemical symbol Pb
is a metal with atomic number 82 and atomic weight of 207.2. It has a melting point of 327.5 C ° and a boiling point of 1,740 C °. Its specific gravity (density) is 11.3gr / cm3. When a lead is freshly cut it has a bluish-white color which tarnishes to a dull grayish color due to oxidation of a small external layer from the air oxygen. Lead has a chrome-silver luster when melted inside liquid.
Lead has been commonly used for thousands of years because it is widespread, easy to extract and work with. It was discovered in 7000 B.C. in the Middle East and is one of the most important metals in the human history along with gold, silver, copper, and tin. It provides a unique protection against radioactivity.
Natural metallic lead has not been found in nature. Lead occurs from mineral ores, mainly galena (PbS). Other common varieties are with silver, copper, bismuth, and iron. Secondary lead minerals are cerussite (PbCO3) and anglesite (PbSO4), which are found in many geographical locations.