Neptunium-238 (Np-238)

Identity

Protons

93

Neutrons

145

Mass number

238

Mass

238.1 ± 1.2 u

Mass excess

47.455 MeV

Spin

2+*

Stability

Half-life: 2.1 days

Natural occurrence

Not found in nature

Decays to

• beta minus → Pu-238