1. Chapter 21 Nuclear Radiation
Nuclear Equations
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

3. Alpha Decay When a radioactive nucleus emits an alpha particle, a new
nucleus forms that has
a mass number that is 4 less than that of the initial nucleus.
an atomic number that is decreased by 2.

4. Balancing Nuclear Equations
In a balanced nuclear equation, the sum of the mass numbers and the sum of the atomic numbers for the nuclei of the reactant and the products must be equal.
MASS NUMBERS
Total = =
251Cf Cm He
Total = =
ATOMIC NUMBERS

5. Guide to Balancing a Nuclear Equation

6. Equation for Alpha Decay
Write an equation for the alpha decay of 222Rn.
STEP 1 Write the incomplete equation
222Rn ?s He
STEP 2 Determine the mass number 222 – 4 = 218
STEP 3 Determine the atomic number – 2 = 84
STEP 4 Determine the symbol of element = Po
STEP 5 Complete the equation
222Rn Po He 84 Po
85 At
86 Rn
4He 2

7. Beta Decay A beta particle is an electron emitted from the nucleus.
forms when a neutron in the nucleus breaks down.
1n e + 1H

8. Writing An Equation for a Beta Emitter
STEP Write an equation for the decay of Potassium,a beta emitter.
42K new nucleus e
STEP 2 Mass number : (same) = 42
STEP 3 Atomic number: = 20
STEP 4 Symbol of element = Ca
STEP K Ca e 0e -1 19 K
20 Ca

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

10. Solution
60Co Ni e 1
beta particle

11. Positron Emission In position emission,
a proton is converted to a neutron and a positron.
1 p n e
the mass number of the new nucleus is the same, but the atomic number decreases by 1.
49Mn Cr e

12. 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.
99mTc Tc 

13. Summary of Types of Radiation
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

14. Summary of Types of Radiation

15. Summary of Changes in Mass and Atomic Numbers
TABLE 9.4

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.

17. Learning Check
What radioactive isotope is produced when a neutron bombards 59Co?
59Co n ? He

18. Solution
mass numbers
= 60
59Co n Mn H e
= 27
atomic numbers

19. Irène and Frédéric Joliot-Curie
Were the 1st to produce a radioactive nuclide through artificial transmutation
Credit: Corbis

20. Transuranic elements in the periodic table
Elements higher than Uranium 92
are transuranic elements