Lead is the heaviest chemical element with a stable isotope.
Its atomic number is 82, and its most abundant stable isotope is lead-208. Elements heavier than lead generally have no stable isotopes, although bismuth-209 was once classified as stable and is now known to undergo extremely slow radioactive decay. Lead therefore marks the conventional boundary for stable nuclides in the periodic table.
Lead is a dense, soft, bluish-gray metal that has been used since antiquity. Roman miners extracted it on a large scale, and the Latin word plumbum gives lead its symbol, Pb. Lead’s density and low melting point made it useful in pipes, weights, ammunition, batteries, and radiation shielding.
The phrase “naturally occurring” can cause confusion because uranium, thorium, and other heavier elements occur naturally but are radioactive. Lead also appears at the end of several radioactive decay chains, including those beginning with uranium-238 and thorium-232.