1. Radioactivity

2. What do we mean by Radioactivity?
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves.
There are numerous types of radioactive decay. The general idea:
An unstable nucleus releases energy to become more stable

3. Early Pioneers in Radioactivity
Rutherford:
Discoverer Alpha and Beta rays 1897
Roentgen:
Discoverer of X-rays 1895
The Curies:
Discoverers of Radium and Polonium
Becquerel:
Discoverer of Radioactivity 1896

4. Kinds of Radioactivity
The three main decays are Alpha, Beta and Gamma

5. Three Common Types of Radioactive Emissions - Penetrability
Alpha particles may be completely stopped by a sheet of paper
beta particles by aluminum shielding
Gamma rays, however, can only be reduced by much more substantial obstacles, such as a very thick piece of lead.

6. Sources of Radioactivity
Primordial - from before the creation of the Earth
Cosmogenic - formed as a result of cosmic ray interactions
Human produced - enhanced or formed due to human actions (minor amounts compared to natural)

7. Alpha Particles (a) Radium Radon R226 Rn222 + a (4He)
Note: This is the atomic weight, which is the number of protons plus neutrons
Alpha Particles (a)
Radium
R226
Radon
Rn222 + p n n p
a (4He)
88 protons
138 neutrons
86 protons
136 neutrons
2 protons
2 neutrons
Note: The 226 refers to the atomic weight, which is the equal to the number of protons plus neutrons
The alpha-particle (a) is a Helium nucleus. It’s the same as the element Helium, with the electrons stripped off !

8. Beta Particles (b) Carbon C14 Nitrogen N14 + e- 6 protons 8 neutrons
electron
(beta-particle)
Note that in beta decay, the atomic mass not change, since the neutron and proton have nearly the same mass…

9. Gamma Rays Neon Ne20 Neon Ne20 +
The gamma from nuclear decay is in the X-ray/ Gamma ray part of the EM spectrum (very energetic!)

10. Bismuth – 214 decays to produce an isotope and an alpha particle
Bismuth – 214 decays to produce an isotope and an alpha particle. Write the reaction.