Pa

Protactinium-231

Protons (Z)

91

Neutrons (N)

140

Mass number

231

Half-Life

32.65 ky

Abundance

100%

Mass

231.036 u

Mass Excess

33,424.3 keV

Spin

3/2-

Discovered

1918

Binding energy per nucleon

7,618 keV

Neutron separation energy

6,821 keV

Proton separation energy

4,727 keV

Decay Mode

SF<3e-10%

Decay chain

Protactinium-231Z 91 · N 14032.65 ky
α~100%
β⁻98.62%
α100%
α~100%
α100%
α~100%
β⁻100%
α~100%
β⁻100%