Caesium

Atomic number55
Atomic weight132.90543
Discovery (year)1860
Atomic radius (A)2.62
Melting point (oC)28.5
Boiling point (oC)703.3
Density (g/cm3)1.87
Specific heat (cal/g oC)0.052
Ionization potential (eV)3.894
Electron Affinity (eV)0.4715