1. Nuclear Radiation

2. Radioactivity
The process by which an unstable nucleus emits one or more particles of energy in the form of electromagnetic radiation

3. After the changes in the nucleus, the element can transform into a different isotope of the same element or change into an entirely different element
This is known as nuclear decay

4. There are 3 major forms of emitted radiation

5. Alpha Particle
A positively charged particle, emitted by some radioactive nuclei, that consists of 2 protons and 2 neutrons

6. Beta Particle
An electron emitted during the radioactive decay of a neutron in an unstable nucleus

7. Alpha vs. Beta

8. Gamma Ray
High-energy electromagnetic radiation emitted by a nucleus during radioactive decay
They are high energy electromagnetic waves that can penetrate into the deepest parts of our bodies

9. 3 major forms of emitted radiation

10. Nuclear Decay
When an unstable nucleus emits alpha or beta particles, the number of protons or neutrons changes
Ex: Radium-226 (an isotope of Radium with the mass number 226) changes to Radon-222 by emitting an alpha particle

11. Nuclear Decay
Nuclear decay processes can be written as equations similar to chemical reactions
The nucleus before decay is like a reactant and is placed on the left side of the equation
The products are placed on the right side

12. Alpha Decay
Alpha Particle is the following… or

13. Beta Decay
Beta particle is the following…

14. Beta Decay
Since an electron has a single negative charge, an electron is given an atomic number of -1 when you write a nuclear decay equation
The beta particle’s mass is so much less than that of a proton or neutron that it is given a mass number of 0
The mass number before and after the decay does not change
The atomic number of the product nucleus increases by 1 because a neutron decays into a proton

15. Radioactive Decay Rates
Half-life – the time required for half of the sample of radioactive nuclei to decay
1st half-life  ½ sample remains
2nd half-life  ¼ sample remains
3rd half-life  1/8 sample remains
4th half life  1/16 sample remains

16. Radioactive Decay Rates
Half-life – the time required for half of the sample of radioactive nuclei to decay
1st half-life  ½ sample remains
2nd half-life  ¼ sample remains
3rd half-life  1/8 sample remains
4th half life  1/16 sample remains

17. 1. Eventually the entire sample will decay
2. With each successive half life, half of the remaining sample decays to form another element

18. Questions 1. What is strontium’s half life?
2. How much strontium do you have to begin with?
3. After the first half-life, how much is left?
4. After how many half-lifes will there be only 125 grams?

19. Calculations with Half-Life
Starting amount
End amount
Start Time (0)
End Time
What is the half life of a 88.0 gram sample of Carbon that decays to 22.0 grams in 11,400 years?
88.0 g
22.0 g
0 years ?
11,400 years

20. More Calculations
Thallium-208 has a half-life of minutes. How long will it take for 100 grams to decay to 25 grams?
The half-life of hafnium-156 is .025 seconds. How long will it take a 440g sample to decay to 1/8 of its original mass?

21. Nuclear Fission
Fission – the process by which a nucleus splits into 2 or more smaller fragments, releasing neutrons and energy
(The production of lighter nuclei from heavy nuclei)

22. Nuclear Fission
Some of the mass of the particles before the fission reaction is turned into energy after the reaction
Matter  energy
Neutrons released by fission can start a chain reaction
When we control the reaction, we can safely use the energy produced to generate electricity in nuclear power plants

23. Nuclear Fission

24. Nuclear Fusion
Fusion – the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy
Energy is also obtained during the fusion process
Stars and sun: energy is produced when H nuclei combine
This energy is provided by the high temperature