Pa

Protactinium-221

Protons (Z)

91

Neutrons (N)

130

Mass number

221

Half-Life

5.9 µs

Abundance

---

Mass

221.022 u

Mass Excess

20,370.0 keV

Spin

9/2-

Discovered

1983

Binding energy per nucleon

7,657 keV

Neutron separation energy

7,979 keV

Proton separation energy

1,609 keV

Decay Mode

αActinium-217100%

Decay chain

Protactinium-221Z 91 · N 1305.9 µs
α100%
α100%
α99.44%
β⁺96.1%
α99.546%
EC100%