Bismuth-211 decays by emitting an alpha particle

When Bismuth-211 decays by emitting an alpha particle, a helium molecule is released together with the new element.

for alpha particle 4He2

4 = mass number
2 = atomic number

Bismuth has an atomic number of 83 therefore the new element produced shoud have a mass number of 207 and atomic number of 81.

This corresponds to approximately 207 Tl 81

D.na is the answer hope this