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Lead is soft and malleable, and has a relatively low melting point.

It is a heavy metal that is denser than most common materials.The similarity of ionization energies is caused by the lanthanide contraction—the decrease in element radii from lanthanum (atomic number 57) to lutetium (71), and the relatively small radii of the elements from hafnium (72) onwards.This is due to poor shielding of the nucleus by the lanthanide 4f electrons.In lead, the inert pair effect increases the separation between its s- and p-orbitals, and the gap cannot be overcome by the energy that would be released by extra bonds following hybridization.It tarnishes on contact with moist air, and takes on a dull appearance the hue of which depends on the prevailing conditions.Lead'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, leaded gasoline, and radiation shielding.With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as stable; lead-208 is the heaviest stable nucleus.(This distinction formerly fell to bismuth, with an atomic number of 83, until its only primordial isotope, bismuth-209, was found in 2003 to decay very slowly.) The four stable isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with a release of energy, but this has not been observed for any of them; their predicted half-lives range from 10 times the current age of the universe).Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution.In 2014, annual global production of lead was about ten million tonnes, over half of which was from recycling.


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