81 Tl 204.38

Thallium

POST-TRANSITION METAL

Phase: Solid

Discovered: William Crookes

Block: P

Summary

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.

Appearance: silvery white

Source: Wikipedia

Physical Properties

Atomic Mass 204.38 u

Density 11.85 g/cm³

Melting Point 577 K

Boiling Point 1746 K

Molar Heat 26.32 J/(mol·K)

Electron Affinity 36.4 kJ/mol

Ionization Energies

1^st: 589.4 kJ/mol

2^nd: 1971 kJ/mol

3^rd: 2878 kJ/mol