LEAD

CARBON GROUP

Atomic number:	82
Group numbers:	14
Period:	6
Electronic configuration:	[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p²
Formal oxidation number:	+2 +4
Electronegativities:	1.8
Atomic radius / pm:	175
Relative atomic mass:	207.2(1)

Lead has been known since ancient times. The origin of the name comes from the Latin word plumbum meaning liquid silver. It is a very soft, highly malleable and ductile, blue-white shiny metal that tarnishes in moist air but is stable in oxygen and water. Lead dissolves in nitric acid and its compounds are toxic by inhalation or ingestion. The toxins have a cumulative effect. Lead is found most often in ores called galena or lead sulfide (PbS). It is used in solder, shielding against radiation and in batteries. The price of 99.5 % pure lead granules is 28.70 € for 500 g.

PHYSICAL PROPERTIES
Density / g dm^-3:	11350	(293 K)
	10678	(m.p.)
Molar volume / cm³mol^-1:	18.26	(293 K)
	19.40	(m.p.)
Electrical resistivity / µΩcm:	20.648	(20 °C)

THERMAL PROPERTIES
Thermal conductivity / W m^-1K^-1:	35.3
Melting point / °C:	327.46
Boiling point / °C:	1749
Heat of fusion / kJ mol^-1:	5.121
Heat of vaporization / kJ mol^-1:	177.8
Heat of atomization / kJ mol^-1:	195.74

IONIZATION ENERGIES
First ionization energy / kJ mol^-1:	715.60
Second ionization energy / kJ mol^-1:	1450.40
Third ionization energy / kJ mol^-1:	3081.50

ABUNDANCE OF ELEMENT
in the atmosphere / ppm:	-
in the Earth's crust / ppm:	8
in the oceans / ppm:	0.003

CRYSTALLOGRAPHIC DATA
Crystal structure:	face-centered cubic
Unit-cell dimensions / pm:	a=495.00
Space group:	Fm3m

ISOTOPES
Isotope	Relative atomic mass	Mass percent (%)
²⁰⁴Pb	203.973029(3)	1.4(1)
²⁰⁶Pb	205.974449(3)	24.1(1)
²⁰⁷Pb	206.975881(3)	22.1(1)
²⁰⁸Pb	207.976636(3)	52.4(1)

REDUCTION POTENTIALS
Balanced half-reaction	E^o / V
Pb⁴⁺ + 2e^- → Pb²⁺	+1.694
Pb²⁺ + 2e^- → Pb(s)	- 0.126
Pb²⁺ + 2e^- → Pb(s)	- 0.14	(1 mol dm^-3 HClO₄)
Pb²⁺ + 2e^- → Pb(s)	- 0.29	(1 mol dm^-3 H₂SO₄)
3PbO₂(s) + 2H₂O + 4e^- → Pb₃O₄(s) + 4OH^-	+0.295
PbO₂(s) + 4H⁺ + 2e^- → Pb²⁺ + 2H₂O	+1.455
PbO₂(s) + 4H⁺ + SO₄^2- + 2e^- → PbSO₄(s) + 2H₂O	+1.685
PbO₂(s) + H⁺ + 2e^- → HPbO₂^-	+0.621
3PbO₃^2- + 10H⁺ + 4e^- → Pb₃O₄(s) + 5H₂O	+2.515
PbO₃^2- + 4H⁺ + 2e^- → PbO(s) + 2H₂O	+2.001
PbO₃^2- + 3H⁺ + e^- → HPbO₂^- + H₂O	+1.547
PbO₃^2- + 6H⁺ + 2e^- → Pb²⁺ + 3H₂O	+2.375
Pb₃O₄(s) + H₂O + 2e^- → 3PbO(s) + 2OH^-	+0.249
Pb₃O₄(s) + 8H⁺ + 2e^- → 3Pb²⁺ + 3H₂O	+2.094
Pb₃O₄(s) + 2H₂O + 2e^- → 3HPbO₂^- + H⁺	- 0.390
PbO(s) + 2H⁺ + 2e^- → Pb(s) + H₂O	+0.249
PbSO₄ + 2e^- → Pb(s) + SO₄^2-	- 0.350
HPbO₂^- + 3H⁺ + 2e^- → Pb(s) + 2H₂O	+0.702
Pb(s) + 2H⁺ + 2e^- → PbH₂	- 1.507