Promethium-149 (Pm-149)

Identity

Protons

61

Neutrons

88

Mass number

149

Mass

148.9 ± 2.3 u

Mass excess

-76.064 MeV

Spin

7/2+*

Stability

Half-life: 2.21 days

Natural occurrence

Not found in nature

Decays to

• beta minus → Sm-149