Determine whether 80Br can undergo radioactive transformatio

Determine whether 80^Br can undergo radioactive transformation by beta^-, beta^+, and electron capture processes. Write the transformation reactions and calculate Q-values for each case.

Solution

The principle used to balance the equation is to balance the charge and mass on each side and change the symbol if the protons changes to that of a different element

35Br80 ----------> 36Kr80 + electron +antinutrino

35Br80 -----------> 34Se80 + 1p0 +nutrini (p = positron, Se = selenium nucleus)

35Br80 + -1e0 ----------> 34Se80 (e = electron, Se = selenium nucleus)

in case of b+ decay

Br80=79.918amu

Kr80=79.9163amu

Se80=79.9165amu

e-=0.000548amu

so in case of b- decay the Q value is 79.91852-79.9163-0.00054=0.00002amux931.3MeV=0.0186MeV(minus)

in case of beta + decay Q value is 79.91852-79.9165-0.00054=0.001amux931.3MeV=1.37MeV

in case of electron capture Q value is

79.91852+0.000548-79.9165=0.002amux931..3MeV=2.39MeV(positive)