Lead

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Lead,  82Pb
A small gray metal cube surrounded by three gray metal nuggets in front of a light gray background
General properties
Pronunciation/ˈlɛd/ (LED)
Appearancemetallic gray
Standard atomic weight (Ar, standard)207.2(1)[1]
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
Blockp-block
Element category  post-transition metal
Electron configuration[Xe] 4f14 5d10 6s2 6p2
Electrons per shell
2, 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, +1, +2, +3, +4 (an amphoteric oxide)
ElectronegativityPauling scale: 1.87 (+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)
Face-centered cubic crystal structure for lead
Speed of sound thin rod1190 m/s (at r.t.) (annealed)
Thermal expansion28.9 µm/(m·K) (at 25 °C)
Thermal conductivity35.3 W/(m·K)
Electrical resistivity208 nΩ·m (at 20 °C)
Magnetic orderingdiamagnetic
Magnetic susceptibility−23.0×10−6 cm3/mol (at 298 K)[2]
Young's modulus16 GPa
Shear modulus5.6 GPa
Bulk modulus46 GPa
Poisson ratio0.44
Mohs hardness1.5
Brinell hardness38–50 MPa
CAS Number7439-92-1
History
Discoveryin the Middle East (7000 BCE)
Main isotopes of lead
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
204Pb 1.4% stable
206Pb 24.1% stable
207Pb 22.1% stable
208Pb 52.4% stable
Isotopic abundances vary greatly by sample
| references
Lead

Lead (pronounce: "/'lɛd/") is a chemical element. Its chemical symbol is Pb, which comes from plumbum, the Latin word for lead.[3] Its atomic number is 82, atomic mass is 207.2 and has a melting point of 327.8°C. It is a very poisonous and heavy metal.

Properties[change | change source]

Physical properties[change | change source]

Lead powder burning

Lead is a shiny, gray-blue poor metal. It gets tarnished easily to a dull gray color. It is soft and malleable. It is very shiny when it is melted. It is very heavy. It is very corrosion-resistant. It is made stronger by adding antimony or calcium. It can form an alloy with sodium. It is toxic to people and animals when swallowed.

Chemical properties[change | change source]

Flame test for lead

Lead burns in air with a grayish-white flame, making toxic fumes of lead(II) oxide. Only the surface is corroded by air. It dissolves in nitric acid to make lead(II) nitrate. It does not dissolve in sulfuric or hydrochloric acid. It reacts with sodium nitrate to make lead(II) oxide and sodium nitrite. It reacts with chlorine to make lead(II) chloride. Lead(II) oxide reacts with lead sulfide to make lead metal and sulfur dioxide.

Chemical compounds[change | change source]

Lead makes chemical compounds in two main oxidation states: +2 and +4. +2 compounds, also known as lead(II) compounds or plumbous compounds, are weak oxidizing agents. +4 compounds, also known as lead(IV) compounds or plumbic compounds, are strong oxidizing agents. Lead compounds are toxic just like the element. The lead halides do not dissolve in water. Lead(IV) oxide is the most common lead(IV) compound. It is a black solid. The lead oxides are all colored, while the other salts are white or colorless. Lead nitrate and lead(II) acetate are the soluble compounds of lead.

+2 compounds

This state is more common than the +4 state. These are weak oxidizing agents. All but the oxides are colorless or white.

Mixed oxidation state compounds

Mixed oxidation state compounds contain lead in the +2 and +4 oxidation state.

+4 compounds

These are less common. They are strong oxidizing agents.

Occurrence[change | change source]

Lead is found very rarely in the earth's crust as a metal. Normally, lead is in the mineral galena. Galena is lead sulfide. Galena is the main lead ore.

History[change | change source]

Lead was used for thousands of years because it is easy to get from the ground and easy to shape and work with. The Romans used lead very commonly. They used it for pipes, drinking vessels, and fasteners.

Preparation[change | change source]

Lead is made from galena. Galena is made pure by froth flotation to get all the impurities out. Then the lead sulfide is roasted in a furnace to make lead(II) oxide. The lead(II) oxide is heated with coke to make liquid lead metal.

Uses[change | change source]

As an element[change | change source]

The dark bricks are made of lead. They are meant to keep people safe from the radioactive material inside.

Lead is used in the ballast of sailboats. It is also used in weight belts for scuba diving. It is also used to make shotgun pellets and bullets for small arms. Some printing presses use lead type because it can be easily shaped. It can be used outside because it does not corrode in water.

Most lead is used in lead acid batteries, though. The lead is oxidized, making electricity. Sheets of lead are used to block sound in some places. Lead is used in radiation shielding. Molten lead can be used as a coolant in nuclear reactors. It used to be mixed with tin to make the pipes in pipe organs. Different amounts of lead make different sounds. In addition, lead has found its usage in solder.

It is used in some solder. It is used in covering for wires that carry high voltage. Some tennis rackets have lead in them to make them heavier. It is used to balance wheels of cars, to make statues, and to make decorative looks in buildings.

As chemical compounds[change | change source]

Many lead compounds are used to make colored glazes in ceramics. Lead can be used in PVC pipes. Lead compounds are added to candles to make them burn better. Lead glass has lead(II) oxide in it. Lead compounds are still used as pigments in some places. Lead compounds were added to gasoline, but are now outlawed. Some lead compounds are semiconductors and are used in photodetectors.

Old uses[change | change source]

Lead was used in many red, yellow, and white pigments in paints. Lead was also used in pesticides. Lead used to be used in pipes carrying water, but now it is not because lead can leach into the water.

Safety[change | change source]

Although it can be safely touched, exposure to lead should be avoided – it is very toxic to humans and other animals when swallowed, and its use is restricted in many countries.

If someone is exposed to lead for a long time, it ruins their kidneys and gives them abdominal pains. Lead also ruins the nervous system. Lead paint was being eaten by children and they were getting lead poisoning.

The best way to understand lead and its properties is to read its MSDS.

Related pages[change | change source]

References[change | change source]

  1. Meija et al. 2016.
  2. Weast, Astle & Beyer 1983, p. E110.
  3. "Discovering Roman Technology". BBC. Retrieved 2009-10-03.