1. Radioactivity

2. Atomic Nuclei
Protons and neutrons are held together by the Strong Nuclear Force
Atoms above 83 protons are Radioactive

3. Nuclear Decay Some isotopes of common elements are unstable
Too many or too few neutrons
They decay into a stable atom
The nucleus will release at least 1 form of nuclear radiation as it decays (gamma, alpha, or beta)

4. Radioactivity
Radioactivity: The process by which an unstable nucleus emits one or more particles or energy

5. Radioactivity

6. Nuclear Power
This is how Nuclear Energy works as well, these radioactive materials produce the energy as they decay

7. Nuclear Radiation - 3 Types
Alpha Particle - helium nucleus
2 protons 2 neutrons
Beta Particle - electron
Gamma Ray - high energy light wave
no mass

8. Rates of Decay – HALF LIFE
Half-Life: How long it takes for a radioactive element to decay into half of its original mass.
The original element is made out of Parent Atoms. These atoms are unstable and radioactive.
At each half-life, half of the existing parent atoms decay into the stable Daughter Atoms.
These Parent atoms are not “lost”, rather they turn into something else – Daughter atoms.

9. Rate of Decay: HALF LIFE
Carbon-14: (5730 year half-life)
It will take 5730 years for 10 g of Carbon-14 to decay down to 5 g of Carbon-14 and 5 g of Carbon-12.
It will take 5730 years for 1000 atoms of Carbon 14 to decay to 500 atoms of Carbon 14 and 500 atoms of Carbon 12.

10. We Use Half-Lives for Dating Things
A rock has 2ooo atoms of Carbon-14 at formation. Today it has only 1ooo atoms of C-14. How old is the rock?
2ooo atoms ÷ 2 = 1ooo atoms (1 half life)
5730 years (1 half-life = 5730 years)
How old is the rock, and how many half-lives have happened, if only 250 atoms of C-14 remains?
2ooo atoms ÷ 2 = 1000 atoms (1 half life)
 1ooo atoms ÷ 2 = 500 atoms (2 half lives)
 500 atoms ÷ 2 = 250 atoms (3 half-lives)
3 half lives = 5730 yrs x 3 = 17,190 yrs

11. Graphing Radiometric Decay

12. Carbon Dating
When something living (organism) dies, it stops taking in new carbon.
The carbon-14 decays and is not replaced while the carbon-12 remains constant.
So the ratio of carbon-12 to carbon-14 tells us how old the formerly living thing is.
t = [ ln (Nf/No) / (-0.693) ] x t1/2

13. Radiometric Dating
The half-life of carbon-14 is 5,730 years, it is only reliable for dating objects up to about 60,000 years old.
The principle of carbon-14 dating applies to other isotopes as well. The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy.
Other Radioactive Elements include:
Potassium-40 (half-life of 1.3 billion years)
Uranium -235 (half-life = 704 million years)
Uranium (half-life = 4.5 billion years)
Thorium-232 (half-life = 14 billion years)
Rubidium-87 (half-life = 49 billion years)