Nuclear reactions involve changes to the nuclei of atoms through the emission or absorption of particles such as alpha particles, beta particles, protons and neutrons. This results in large changes in mass and huge amounts of energy. Nuclear equations must balance the mass numbers on each side and the nuclear charges to show the nuclear reaction. Examples are given of balancing nuclear equations involving alpha and beta particle emission.

1. Nuclear Equations

2.  Nuclear reactions are different from chemical
reactions
Nuclear Reactions vs Chemical
Reactions
Chemical
Reactions
Mass is
conserved
(doesn’t
change)
Small
energy
changes
No changes in the
nuclei; involve ONLY
valance electrons
Nuclear
Reactions
Small
changes in
mass
Huge energy
changes
protons, neutrons,
electrons and
gamma rays can be
lost or gained

3. Particles Involved in Nuclear
Equations
Common name Symbol
Helium-4 nucleus alpha particle a, 2
4 𝐻𝑒
electron
beta particle
β-, −1
0
𝛽, e-
positron β+, +1
0
𝛽, e+
proton p, 1
1
𝑝, 1
1
𝐻
neutron n, 0
1
𝑛
photon gamma ray γ

4. Balancing Nuclear Equations
 The sums of mass numbers (left superscripts) on each side
must be equal.
 The sums of atomic numbers or nuclear charges (left
subscripts) on each side of the equation must be equal.
Examples:
92
238
𝑼 2
4
𝑯𝒆 + 90
234
𝑻𝒉
82
214
𝑷𝒃 −1
0
𝜷 + 83
214
𝑩𝒊
 Charges are not included in nuclear equations except to
distinguish between the two types of b particles

5. Balancing Nuclear Equations
1. 217At 213Bi + ?
2. 231Th −1
0
𝛽 + ?
3. 208Tl −1
0
𝛽 + ?

6. Balancing Nuclear Equations
1. 85
217
𝐀𝐭 83
213
𝐁𝐢 + 2
4
𝐇𝐞
2. 90
231
𝐓𝐡 −1
0
𝛽 + 91
231
𝐏𝐚
3. 81
208
𝐓𝐥 −1
0
𝛽 + 82
208
𝐏𝐛