1. Radioactivity

2. What is Radioactivity?
Radioactivity: the release of high energy particles from the nucleus of an unstable atom to make the atom more stable.

3. What is Radioactivity?
All elements are made up of protons, neutrons, and electrons
Protons and neutrons are held together by a strong nuclear force, which prevents the positive protons from repelling each other out of the nucleus.

4. What is Radioactivity?
BUT!…the Strong Nuclear Force only works for small distances.
As atomic number increases, the nucleus increases in size, and the strength of the Strong Force decreases.
Atomic Number
Strong Force =

5. 3 Types of Nuclear Radiation (video)
Alpha Radiation:
Emits Alpha Particles
2 Protons and 2 Neutrons lost from nucleus
Positively charged
Most massive particle.
Mass of atom decreases by 4

6. 3 Types of Nuclear Radiation
Beta Radiation:
Emits Beta Particles
Fast-moving electrons emitted when a neutron decays to form a proton and an electron.
Negatively charged
Faster and much smaller than Alpha particles.
Mass of atom doesn’t change

7. 3 Types of Nuclear Radiation
Gamma Radiation:
Emits Gamma Rays
Electromagnetic rays called photons
Have very high energy
Have no charge
Have no mass and are very small
Are the most penetrating
Mass of atom doesn’t change

8. Nuclear Fission (video)
Nuclear Fission: the splitting of an atomic nucleus into 2 smaller nuclei.
Chain Reaction: On-going series of fission reactions
Nagasaki, Japan
Aug. 9, 1945
Harris Nuclear Facility
Raleigh, NC

9. Nuclear Fusion (video)
Nuclear Fusion: Combining of 2 nuclei with low masses to form 1 nucleus of larger mass (the opposite of fission)

10. Fraction of Sample Remaining Mass of Sample Remaining
Half Life
Half life is the time it takes for ½ of a sample to breakdown.
Ex. A 12 gram sample of P-32 decays by beta emission with a half life of 14 days.
Number of half-lives
Time
Fraction of Sample Remaining
Mass of Sample Remaining
1/1
12 g 1 14
1/2
6 g 2 28
1/4
3 g 3 42
1/8
1.5 g 4 56
1/16
0.75 g