Lead

Lead (pronounce: "/'lɛd/") is a chemical element. Its chemical symbol is Pb, which comes from plumbum, the Latin word for lead. 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, and is also the ending element to the stable elements, although the next element, bismuth, is so weakly radioactive that it can be considered stable for practical purposes.

Lead, ₀₀Pb

Lead
Pronunciation	/ˈlɛd/ ​(led)
Appearance	metallic gray
Standard atomic weight Ar°(Pb)
	[206.14, 207.94]
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 thallium ← lead → bismuth
Group	group 14 (carbon group)
Period	period 6
Block	p-block
Electron configuration	[Xe] 4f14 5d10 6s2 6p2
Electrons per shell	2, 8, 18, 32, 18, 4
Physical properties
Phase at STP	solid
Melting point	600.61 K ​(327.46 °C, ​621.43 °F)
Boiling point	2022 K ​(1749 °C, ​3180 °F)
Density (near r.t.)	11.34 g/cm3
when liquid (at m.p.)	10.66 g/cm3
Heat of fusion	4.77 kJ/mol
Heat of vaporization	179.5 kJ/mol
Molar heat capacity	26.650 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, +1, +2, +3, +4 (an amphoteric oxide)
Electronegativity	Pauling scale: 1.87 (+2)
Ionization energies	1st: 715.6 kJ/mol 2nd: 1450.5 kJ/mol 3rd: 3081.5 kJ/mol
Atomic radius	empirical: 175 pm
Covalent radius	146±5 pm
Van der Waals radius	202 pm
Spectral lines of lead
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	1190 m/s (at r.t.) (annealed)
Thermal expansion	28.9 µm/(m⋅K) (at 25 °C)
Thermal conductivity	35.3 W/(m⋅K)
Electrical resistivity	208 nΩ⋅m (at 20 °C)
Magnetic ordering	diamagnetic
Molar magnetic susceptibility	−23.0×10−6 cm3/mol (at 298 K)
Young's modulus	16 GPa
Shear modulus	5.6 GPa
Bulk modulus	46 GPa
Poisson ratio	0.44
Mohs hardness	1.5
Brinell hardness	38–50 MPa
CAS Number	7439-92-1
History
Discovery	in the Middle East (7000 BCE)
Symbol	"Pb": from Latin plumbum
Isotopes of lead
Main isotopes 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

Lead

Properties

Physical properties

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

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

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.

• Lead(II) acetate, colorless soluble
• Lead(II) arsenate, insoluble former pesticide
• Lead(II) bromide, insoluble
• Lead(II) carbonate, white, used as pigment
• Lead(II) chloride, insoluble
• Lead(II) nitrate, soluble, colorless
• Lead(II) oxide, red or yellow
• Lead(II) sulfate, white, found in lead acid batteries
• Lead(II) sulfide, black, common as mineral

Mixed oxidation state compounds

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

• Lead(II,IV) oxide, red, oxidizing agent

+4 compounds

These are less common. They are strong oxidizing agents.

• Lead(IV) acetate, oxidizing agent, colorless
• Lead(IV) oxide, dark brown, oxidizing agentCobalt compounds are chemical compounds containing cobalt ions.

• 
  Lead(II) chloride
• 
  Lead(II) nitrate
• 
  Lead(IV) oxide
• 
  Lead(II,IV) oxide
• 
  Lead(II) oxide

Occurrence

• 
  Lead found in the ground
• 
  Galena

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

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

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

As an element

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

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

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

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

• List of common elements
• Lead poisoning