1. Unstable Nuclei and Radioactive Decay

2. History Alchemy Arose in the Persian empire
The study of changing one substance into another
Goal to obtain immortality and ultimate knowledge

4. Nuclear reactions involve a change in the nucleus of the atom
Changing one substance into another

5. Radioactivity
Chemical rxns involve a change in the e- configuration of an element
No change in the nucleus of the element
Some substances spontaneously emit rays and particles (radiation)
Cause a change in the identity of the atom
Unstable systems
By releasing energy become more stable
Radioactive decay – unstable nuclei lose energy by emitting radiation

6. Types of Radiation Alpha radiation Beta Radiation 2+ charge 2 p+, 2 n0
Symbol
42He a
22688Ra  22286Rn + 42He
Beta Radiation
1- charge
1 e-
Symbol
0-1b
146C  147N + 0-1b

7. Types of Radiation (….Continued)
Gamma Radiation
AKA gamma rays
NO MASS
High energy
Symbol
00g
Usually accompany alpha and beta radiation
Alone don’t make a new particle
23892U  23490Th + 42He + 200g

9. Nuclear Stability
Stability is based on ratio of n0 to p+

10. Amountf= (Amounti) (1/2)t/T
Half Life
Time it takes for half a radioisotope’s nuclei to decay into it’s product
Amountf= (Amounti) (1/2)t/T
T = half life
t= time elapsed