Bismuth-209 (Bi-209)

Identity

Protons

83

Neutrons

126

Mass number

209

Mass

209.0 ± 1.5 u

Mass excess

-18.259 MeV

Spin

9/2-*

Stability

Half-life: 2.01 × 10¹⁹ years

Natural occurrence

100.00 % of bismuth

Decays to

• alpha → Tl-205

Produced by

• Po-209