- 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
Atomic Mass (u)
577.15
Melting Point (K)
1746
Boiling Point (K)
11.85
Density (solid: g/cm³, gas: g/liter)
2.1
Atomic Radius (Å)
1.45
Covalent Radius (Å)
2.04
Electronegativity
6.11
First Ionization Energy (eV)
36.4
Electron Affinity
6
Number of Shells
3
Electron Valency
2, 8, 18, 32, 18, 3
Electron Shell Occupations
0.13
Specific Heat (J/g)