Atomic Number (# of protons)

81

Mass (amu)

204.4

Density

11.85 g/cm³ (20⁰C, 1 atm)

Electron Configuration

[Xe]4f¹⁴5d¹⁰6s²p¹

Oxidation States (bold = most stable)

+3,+1

Atomic Radius (pm)

170

Ionic Radius (pm)

(+1)159

Electronegativity

1.4

Melting Point (⁰C, 1 atm)

304

Electron Affinity (eV)

0.2

Boiling Point(⁰C, 1 atm)

1473

1^st Ionization energy (eV)

6.11

Enthalpy of Fusion (kJ/mole)

4.27

2^nd Ionization Energy (eV)

Enthalpy of Vaporization (kJ/mole)

162.1

3^rd Ionization Energy (eV)

Specific Heat Capacity ( J/ (g K), 25⁰C, 1 atm)

0.13