Lead (pronounce: "/'lɛd/") is a chemical element . Its chemical symbol is Pb , which comes from plumbum , the Latin word for lead.[6] 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.[7]
Quick Facts Pronunciation, Appearance ...
Lead, 00 Pb Pronunciation (led ) Appearance metallic gray [ 206.14 , 207.94 ][1]
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 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
Oxidation states −4, −2, −1, 0,[2] +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 leadNatural 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 Discovery in the Middle East (7000 BCE ) Symbol "Pb": from Latin plumbum
Main isotopes[4]
Decay
abun dance
half-life (t 1/2 )
mode
pro duct
202 Pb
synth
5.25× 104 y
ε
202 Tl
204 Pb
1.40%
stable
205 Pb
trace
1.73× 107 y
ε
205 Tl
206 Pb
24.1%
stable
207 Pb
22.1%
stable
208 Pb
52.4%
stable
209 Pb
trace
3.253 h
β−
209 Bi
210 Pb
trace
22.20 y
β−
210 Bi
211 Pb
trace
36.1 min
β−
211 Bi
212 Pb
trace
10.64 h
β−
212 Bi
214 Pb
trace
26.8 min
β−
214 Bi
Isotopic abundances vary greatly by sample
[5]
Category: Lead | references
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Lead