Lead

Lead, 82Pb
A small gray metal cube surrounded by three gray metal nuggets in front of a light gray background
Lead
Pronunciation/ˈlɛd/ (led)
Appearancemetallic gray
Standard atomic weight Ar°(Pb)
Lead in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Sn

Pb

Fl
thalliumleadbismuth
Atomic number (Z)82
Groupgroup 14 (carbon group)
Periodperiod 6
Block  p-block
Electron configuration[Xe] 4f14 5d10 6s2 6p2
Electrons per shell2, 8, 18, 32, 18, 4
Physical properties
Phase at STPsolid
Melting point600.61 K ​(327.46 °C, ​621.43 °F)
Boiling point2022 K ​(1749 °C, ​3180 °F)
Density (near r.t.)11.34 g/cm3
when liquid (at m.p.)10.66 g/cm3
Heat of fusion4.77 kJ/mol
Heat of vaporization179.5 kJ/mol
Molar heat capacity26.650 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 978 1088 1229 1412 1660 2027
Atomic properties
Oxidation states−4, −2, −1, 0,[3] +1, +2, +3, +4 (an amphoteric oxide)
ElectronegativityPauling scale: 2.33 (in +4), 1.87 (in +2)
Ionization energies
  • 1st: 715.6 kJ/mol
  • 2nd: 1450.5 kJ/mol
  • 3rd: 3081.5 kJ/mol
Atomic radiusempirical: 175 pm
Covalent radius146±5 pm
Van der Waals radius202 pm
Color lines in a spectral range
Spectral lines of lead
Other properties
Natural occurrenceprimordial
Crystal structureface-centered cubic (fcc)
Lattice constant
Face-centered cubic crystal structure for lead
495.08 pm
Thermal expansion28.9 µm/(m⋅K) (at 25 °C)
Thermal conductivity35.3 W/(m⋅K)
Electrical resistivity208 nΩ⋅m (at 20 °C)
Magnetic orderingdiamagnetic
Molar magnetic susceptibility−23.0×10−6 cm3/mol (at 298 K)[4]
Young's modulus16 GPa
Shear modulus5.6 GPa
Bulk modulus46 GPa
Speed of sound thin rod1190 m/s (at r.t.) (annealed)
Poisson ratio0.44
Mohs hardness1.5
Brinell hardness38–50 MPa
CAS Number7439-92-1
History
DiscoveryMiddle East (7000 BCE)
Symbol"Pb": from Latin plumbum
Isotopes of lead
Main isotopes[5] Decay
abun­dance half-life (t1/2) mode pro­duct
202Pb synth 5.25×104 y ε 202Tl
204Pb 1.40% stable
205Pb trace 1.73×107 y ε 205Tl
206Pb 24.1% stable
207Pb 22.1% stable
208Pb 52.4% stable
209Pb trace 3.253 h β 209Bi
210Pb trace 22.20 y β 210Bi
211Pb trace 36.1 min β 211Bi
212Pb trace 10.64 h β 212Bi
214Pb trace 26.8 min β 214Bi
Isotopic abundances vary greatly by sample[6]
 Category: Lead
| references

Lead is a chemical element; it has symbol Pb (from Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. 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. Lead is toxic, even in small amounts, especially to children.

Lead is a relatively unreactive post-transition metal. 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. Compounds of lead 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, lead tends to bond with itself; it can form chains and polyhedral structures.

Since lead is easily extracted from its ores, prehistoric people in the Near East were aware of it. Galena is a principal ore of lead which often bears silver. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. Lead played a crucial role in the development of the printing press, as movable type could be relatively easily cast from lead alloys.[7] In 2014, the annual global production of lead was about ten million tonnes, over half of which was from recycling. 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.

Lead is a devastating and persistent 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's toxicity was first documented by ancient Greek and Roman writers, who noted some of the symptoms of lead poisoning, but became widely recognized in Europe in the late 19th century.

  1. ^ "Standard Atomic Weights: Lead". CIAAW. 2020.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "Observation of the lead carbonyls PbnCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon". The Journal of Chemical Physics. 122 (3): 034505. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.
  4. ^ Weast, Astle & Beyer 1983, p. E110.
  5. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  6. ^ Meija et al. 2016.
  7. ^ Theodore Low De Vinne 1899, pp. 9–36.