- Atomic Radius (Å)
Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air.
81
Atomic Number
204.38 u
Atomic Mass
577.15 K
Melting Point
1746 K
Boiling Point
11.85 g/cm³
Density
2.1 Å
Atomic Radius
1.45 Å
Covalent Radius
2.04
Electronegativity
6.11 eV
First Ionization Energy
36.4
Electron Affinity
6
Number of Shells
3
Electron Valency
2, 8, 18, 32, 18, 3
Electron Shell Occupations
0.13 J/g
Specific Heat