Balancing nuclear
equations
1.
What radiation will be emitted when Bi-211 decomposes to Tl-201?
In this problem, the reactant is Bi-211 and the products are Tl-201 and
unknown radiation.
211 Bi
83
→ 20781Tl + ?
(i)
Check the mass numbers (or superscripts): 211 → 207 + x
(ii)
Check the atomic numbers (subscripts): 83 → 81 + y
Therefore:
x = 4 and y = 2.
Which particle has a mass of 4 and a charge of +2? Answer: alpha particles
The balanced nuclear equation is:
211
83Bi
→ 20781Tl + 42He.
The balanced nuclear equation shows alpha particle as one of the products. This means that
the nuclear decay involves the loss of an alpha particle from a nucleus. Scientists call this
reaction an alpha decay.
2.
Which of these equations is balanced?
226 Ra
88
→ 22286Rn + 42He + γ
226 Ra
88
→ 22286Rn + 42 He
Answer: Both are balanced because in each equation the sum of superscripts of the left equal
to that on the right, and the sum of subscripts on the left equal to that on the right. This is an
alpha decay process.
Example sheet