1. Nuclear Radiation Natural Radioactivity Nuclear Equations
Producing Radioactive Isotopes
Half-Life
Nuclear Fission and Fusion

2. Subatomic Particles Protons- plus charge In the nucleus
Neutrons- neutral
Electrons - negative charge
Outside the nucleus

3. Nuclear Symbols Mass number (p+ + no) Element symbol Atomic number
(number of p+)

4. RADIOACTIVITY
Nuclei of unstable isotopes called radioisotopes gain stability by undergoing changes
These changes are always accompanied by large amounts of energy
Discovery of radioactivity dealt a blow to Dalton’s theory that atoms are indivisible

5. Radiation Radiation comes from the nucleus of an atom.
Unstable nucleus emits a particle or energy  alpha
 beta
 gamma

6. Same as a helium nucleus
Alpha Particle
Same as a helium nucleus
(He) 4
2 He or 
Two protons
Two neutrons

7. Beta Particle  e or  1 An electron emitted from the nucleus
e or  1
A neutron in the nucleus breaks down
n H + e

8. Gamma  Radiation Pure radiation
Like an X-ray but comes from the nucleus

9. Radiation Protection Shielding alpha – paper, clothing
beta – lab coat, gloves
gamma- lead, thick concrete
Limit time exposed
Keep distance from source

10. Radiation Protection

11. Balancing Nuclear Equations
In the reactants and products
Atomic numbers must balance
and
Mass numbers must balance

12. Alpha decay

13. Beta decay
234Th ® 234Pa e 1
beta particle

14. No change in atomic or mass number
Gamma radiation
No change in atomic or mass number
11B 11B 
boron atom in a
high-energy state

15. Types of Radioactive Decay
gamma ray production (g):
positron production :
electron capture: (inner-orbital electron is captured by the nucleus) e 1

16. Types of Radiation

17. Learning Check NR1
Write the nuclear equation for the beta emitter Co-60.

18. Solution NR1
Write the nuclear equation for the
Beta emitter Co-60.
60Co Ni e

19. Half-Life of a Radioisotope
The time for the radiation level to fall (decay) to one-half its initial value
decay curve
8 mg 4 mg 2 mg mg
initial 1
half-life 2 3

20. Examples of Half-Life Isotope Half life C-15 2.4 sec Ra-224 3.6 days
I days
C years
U years

21. Learning Check NR3
The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours?

22. Solution NR3 t1/2 = 13 hrs 26 hours = 2 x t1/2 Amount initial = 64mg
Amount remaining = 64 mg x ½ x ½
= 16 mg

23. Nuclear Fission Fission large nuclei break up
235U n Ba Kr + 3 1n +
Energy

24. Fission

25. Nuclear Fusion Fusion small nuclei combine 2H + 3H 4He + 1n + 1 1 2 0
Occurs in the sun and other stars
Energy

26. Learning Check NR4 Indicate if each of the following are
Fission (2) fusion
Nucleus splits
Large amounts of energy released
Small nuclei form larger nuclei
Hydrogen nuclei react
Energy

27. Solution NR4 Indicate if each of the following are Fission (2) fusion
Nucleus splits
Large amounts of energy released
Small nuclei form larger nuclei
Hydrogen nuclei react

28. Energy and Mass
Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:
DE = Dmc2
Dm = mass defect
DE = change in energy
c = speed of light
Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.