Thallium vs Lead

Side-by-side comparison of Thallium (Tl, element 81) and Lead (Pb, element 82) by atomic structure and physical properties.

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PropertyTl Thallium Pb Lead
Atomic number8182
SymbolTlPb
NameThalliumLead
Categorypost-transition-metalpost-transition-metal
Standard Atomic Weight204.3835 u207.2 u
Period66
Group1314
Blockpp
Phase at STPSolidSolid
Electron configuration[Xe]4f145d106s26p1[Xe]4f145d106s26p2
Oxidation states[-5, -2, -1, 1, 2, 3][-4, -2, -1, 0, 1, 2, 3, 4]
Electronegativity (Pauling)1.622.33
Electron affinity0.320053 eV0.356721 eV
Density1.18e+4 kg/m³1.1342e+4 kg/m³
Melting point303.85 °C327.46 °C
Boiling point1472.85 °C1748.85 °C
Discovery year18612021

Key Differences

PropertyTl ThalliumPb Lead
Standard Atomic Weight204.3835 u ↓ lower207.2 u ↑ higher
Density1.18e+4 kg/m³ ↑ higher1.1342e+4 kg/m³ ↓ lower
Melting point303.85 °C ↓ lower327.46 °C ↑ higher
Boiling point1472.85 °C ↓ lower1748.85 °C ↑ higher
Electronegativity (Pauling)1.62 ↓ lower2.33 ↑ higher
Electron affinity0.320053 eV ↓ lower0.356721 eV ↑ higher
Group13 14
Electron configuration[Xe]4f145d106s26p1 [Xe]4f145d106s26p2
Discovery year1861 2021