Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome. Galena is a principal ore of lead which often bears silver. Since lead is easily extracted from its ores, prehistoric people in the Near East were aware of it. Like the lighter members of the group, lead tends to bond with itself it can form chains and polyhedral structures. Exceptions are mostly limited to organolead compounds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Its weak metallic character is illustrated by its amphoteric nature lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Lead is a relatively unreactive post-transition metal. Lead is toxic, even in small amounts, especially to children. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. It tarnishes to a dull gray color when exposed to air.
When freshly cut, lead is a shiny gray with a hint of blue. Lead is soft and malleable, and also has a relatively low melting point. It is a heavy metal that is denser than most common materials. HCP metals are not as ductile as FCC metals.Lead is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. Metals containing HCP structures include beryllium, magnesium, zinc, cadmium, cobalt, thallium, and zirconium. However, unlike the fcc, it is not a Bravais lattice as there are two nonequivalent sets of lattice points. Hexagonal close packed (hcp) is one of the two simple types of atomic packing with the highest density, the other being the face centered cubic (fcc). The middle layer contains three atoms nestled between the atoms of the top and bottom layers, hence, the name close-packed. The top and bottom layers contain six atoms at the corners of a hexagon and one atom at the center of each hexagon. In a hexagonal close-packed (HCP) arrangement of atoms, the unit cell consists of three layers of atoms. These metals possess low strength and high ductility. Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium. This structure, along with its hexagonal relative (hcp), has the most efficient packing (74%). In a face-centered cubic arrangement, a unit cell contains (8 corner atoms × ⅛) + (6 face atoms × ½) = 4 atoms.
These metals possess high strength and low ductility. Metals containing BCC structures include ferrite, chromium, vanadium, molybdenum, and tungsten. The packing is more efficient (68%) than simple cubic and the structure is a common one for alkali metals and early transition metals. In a body-centered cubic arrangement, a unit cell contains (8 corner atoms × ⅛) + (1 center atom × 1) = 2 atoms. In a body-centered cubic (BCC) arrangement of atoms, the unit cell consists of eight atoms at the corners of a cube and one atom at the body center of the cube. The three most common basic crystal patterns are: There are 14 general types of such patterns known as Bravais lattices. It is this repeated pattern which control properties like strength, ductility, density, conductivity (property of conducting or transmitting heat, electricity, etc.), and shape. The forces of chemical bonding causes this repetition. A crystal lattice is a repeating pattern of mathematical points that extends throughout space. In metals, and in many other solids, the atoms are arranged in regular arrays called crystals. A possible crystal structure of Gold is face-centered cubic structure.
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