1. Chapter 9 Nuclear Radiation
9.2
Nuclear Equations

2. Balancing Nuclear Equations
In a balanced nuclear equation, particles are emitted from the nucleus, and
the mass number and atomic number may change
the sum of the mass numbers and the sum of the atomic numbers are equal for the reactants and the products
Mass number sum: =
251Cf  Cm He
Atomic number sum: =

3. Guide to Balancing Nuclear Equations

4. Alpha Decay
When a radioactive nucleus emits an alpha particle, a new nucleus forms with a mass number that is decreased by 4 and an atomic number that is decreased by 2.

5. Equation for Alpha Emission
Write an equation for the alpha decay of Rn-222.
Step 1 Write the incomplete nuclear equation.
Step 2 Determine the missing mass number.
222 – 4 = 218
Step 3 Determine the missing atomic number.
86 – 2 = 84

6. Equation for Alpha Emission
Write an equation for the alpha decay of Rn-222.
Step 4 Determine the symbol of the new nucleus.
84 = Po
Step 5 Complete the nuclear equation.

7. Beta Emission
A beta particle is an electron emitted from the nucleus when a neutron in the nucleus breaks down, increasing the atomic number by 1.

8. Equation for Beta Emission
Write an equation for the decay of 42K, a beta emitter.
Step 1 Write the incomplete nuclear equation.
Step 2 Determine the missing mass number.
42 – 0 = 42
Step 3 Determine the missing atomic number.
19  (1) = 20

9. Equation for Beta Emission
Write an equation for the decay of 42K, a beta emitter.
Step 4 Determine the symbol of the new nucleus.
20 = Ca
Step 5 Complete the nuclear equation.

10. Learning Check
Write the nuclear equation for the beta decay of 60Co.

11. Solution Write the nuclear equation for the beta decay of 60Co.
Step 1 Write the incomplete nuclear equation.
Step 2 Determine the missing mass number.
60 – 0 = 60
Step 3 Determine the missing atomic number.
27  (1) = 28

12. Solution Write the nuclear equation for the beta decay of 60Co.
Step 4 Determine the symbol of the new nucleus.
28 = Ni
Step 5 Complete the nuclear equation.

13. Positron Emission In positron emission,
a proton is converted to a neutron and a positron.
the mass number of the new nucleus is the same, but the atomic number decreases by 1.

14. Gamma Radiation In gamma radiation,
energy is emitted from an unstable nucleus, indicated by m following the mass number
the mass number and the atomic number of the new nucleus are the same

15. Summary of Types of Radiation

16. Producing Radioactive Isotopes
Radioactive isotopes are produced
when a stable nucleus is converted to a radioactive nucleus by bombarding it with a small particle
in a process called transmutation
When nonradioactive B-10 is bombarded by an alpha particle, the products are radioactive N-13 and a neutron.

17. Learning Check
What radioactive isotope is produced when a neutron bombards 98Tc, releasing an alpha particle?

18. Solution
What radioactive isotope is produced when a neutron bombards 98Tc, releasing an alpha particle?
Step 1 Write the incomplete nuclear equation.
Step 2 Determine the missing mass number.
 4 = 95
Step 3 Determine the missing atomic number.
27  2 = 25

19. Solution
What radioactive isotope is produced when a neutron bombards 98Tc, releasing an alpha particle?
Step 4 Determine the symbol of the new nucleus.
25 = Mn
Step 5 Complete the nuclear equation.