1. Nuclear Applications

2. 1H is stable with 0 neutrons
iso
Natural Abundance
half-life
Decay Mode
Decay Energy
Decay Product 1H %
1H is stable with 0 neutrons 2H
0.0115%
2H is stable with 1 neutron 3H
trace
12.32y β−
3He

3. Source of Radioisotopes - radioactive isotope of an element
1. Created from stable isotopes
neutron bombardment—disturbs the 1:1 OR 1.5:1 N:P ratio and causes instability in the nucleus
Naturally radioactive elements
All elements heavier than bismuth are naturally radioactive due to their instability.
They are artificially created.
All elements heavier than uranium are formed by bombarding a heavy atom with neutrons or alpha particles.

4. Properties of Radioactive Elements
Can cause some other substances to fluoresce, or glow in the dark.
Prolonged exposure can cause damage to cells.
This is the hand of a doctor that performed x-rays for 15 years without protecting his body.

5. Uses of Radioactivity Medical
Radiation therapy for cancer – chemotherapy
In low doses, ionizing radiation induces cancer.
In high doses it destroys cells.
Radioactive tracers for medical diagnosis and research- nuclear medicine imaging
radioactive tags and monitor the location of the radioactivity with time

6. Uses of Radioactivity Food Irradiation Smoke detectors Nuclear power
Food can be irradiated with g rays from 60Co or 137Cs.
Irradiated milk has a shelf life of 3 mo. without refrigeration.
USDA has approved irradiation of meats and eggs.
Smoke detectors
Nuclear power

7. Uses of Radioactivity Radioactive Dating
Fossils are dated by knowing the ratio of parent element (radioactive) to daughter element (what is left after radioactive decay.)
Two things must be known: length of half-life and ratio of parent:daughter.

8. Half Life of Radioisotopes
Half life is the amount of time it takes for one half of a radioactive element to change from the parent (radioactive) to daughter (product) element
Example: The half life of Ra-226 is 1600 years. How much of a 10.0 gram sample will remain after 3 half lives?
1 half-life g  5.0 g
2 half-lives 5.0 g  2.5 g
3 half-lives 2.5 g  1.25 g
4800 years!!!

9. Graph of Half Life

10. Radioactive Dating
The Carbon-14 isotope is used for wood, bones, tissue, anything that used to be alive.
All living things contain carbon, and part of the carbon is C-14 (Most is C-12). After something dies, it stops exchanging carbon with the atmosphere and the C-14 begins to decay.
Because we know the half-life of C-14 to be 5730 years, we can measure the amount of C-14 left and calculate how long the organism has been dead.

11. Skittles Lab!