Atomic Element Z = 81 • Post-Transition Metal
Thallium (Tl) — Atomic Data, Electron Shells & Reactions
Thallium (symbol Tl, atomic number 81) has a standard atomic weight of 204.38 u and ground-state configuration [Xe] 4f14 5d10 6s2 6p1.
Atomic Number (Z)
81
IUPAC Symbol
Tl
Standard Atomic Weight
204.38 g/mol
Period / Group / Block
6 / 13 / p-block
Condensed Electron Config
[Xe] 4f14 5d10 6s2 6p1
Full Subshell Config
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p1
Principal Shell Occupancy
[2, 8, 18, 32, 18, 3]
Pauling Electronegativity
1.62
First Ionization Energy
589 kJ/mol
Covalent Radius
145 pm
Melting Point
577 K (303.85 °C)
Boiling Point
1746 K (1472.85 °C)
Density
11.85 g/cm³
Oxidation States
+1, +3
Tl (Z=81) — Valence shell highlighted in vermilion