1. Radioactivity Part 2 Nuclear Chemistry

2. Three types

3. Alpha Radiation Uses Found in Nature Effects
Polonium-210 is an alpha emitter. During radioactive decay, it loses two protons, and becomes a lead-206 atom, which is stable (i.e., nonradioactive).
Uses
Radium-226 to treat cancer
Polonium-210 eliminates static in paper mills by alpha particles attracting loose electrons
Americium-241 in smoke detectors to help create electrical current (smoke will interrupt the current and set off the alarm)
Found in Nature
Radium-226 & Uranium-238 are present in all rocks, soil, water
Mining tends to increase exposure in humans & the environment
Effects
Lack energy to penetrate skin (must be inhaled, ingested, absorbed)
Greatest hazard to lung tissue (inhaled)
Inside us it’s the most dangerous (Causes cancer)

4. Human Exposure to Radioactivity
Radon (Radioactive Gas) is part of the radioactive decay chain of naturally occurring uranium in soil. You can’t see, smell or taste radon.
Health effect = lung cancer
Test every 2 years 
Above 4.0 pCi/L of radan in the air should be dealt with. 

5. important for the management/disposal of radioactive materials
During decay – Radon-222 is commonly produced.
It’s a gas and seeps up through the soil into the air. It can accumulate into high concentrations in basements.
Gives off alpha particles
Its short half life means it emits alpha particles at a high rate.

6. Beta Radiation Uses Found in Nature Effects Iodine-131 to treat cancer
Strontium-90 is a tracer in medical & agricultural fields
Tritium used for luminous exit signs, dials and watches
Carbon-14 for dating organic matter
Found in Nature
Carbon-14 & Potassium-40 found in our bodies
Effects
Lack energy to penetrate solid material
Direct exposure can redden or burn the skin
Kills cells
Iodine-131 accumulates in the thyroid gland
Strontium-90 accumulates in bone and teeth

7. Gamma Radiation Uses Found in Nature Effects
Cesium-137 cancer treatment, measurements (soil density, packaging, oil wells)
Cobalt-60 sterilize medical equipment, treats cancer, pasteurizes foods and spices, measures thickness of metals
Technetium-99 used for medical imaging (xrays)
Can inspect welds and metal parts for leaks and defects
Found in Nature
Potassium-40 found in soil and water, meats and foods high in potassium like bananas
Effects
Can improve durability of wood and plastics
Radiation sickness
Nothing really stops it but lead or concrete can slow it down

8. Your annual Radiation Dose
Average annual radiation dose in US is 360 mrem.
The normal permissible limit is 5,000 mrem for those who work around radiation.

9. Radiation Detection Film badge Geiger-Muller counter
Approximate amounts of radiation can be detected by the following devices:
Film badge
Geiger-Muller counter
Scintillation counter 9

10. Half-life
Half-life – time required for half of the original sample of radioactive nuclides to decay
Half of the radioactive parent atoms decay after one half-life. Half of the remainder decay after another half-life and so on……..

11. Half life
The decay of radioisotopes can be used to measure the material’s age.
= radioisotope
= new atom formed
After 2 half lives another half have decayed (12 altogether)
After 3 half lives another 2 have decayed (14 altogether)
At start there are 16 radioisotopes
After 1 half life half have decayed (that’s 8)

12. Decay Curve
shows the decay of radioactive atoms and the remaining radioactive sample.
A very important point here is that we cannot predict when a particular entity will decay.
We do know though, that if we had a large sample of a radioactive substance, some number will decay after a given amount of time.
Some radioactive substances have a very high “rate of decay”, while others have a very low decay rate.

13. Application of Half Life
Radioactive dating
a process used to determine the approximate age of an object.
Ex. Carbon -14, a radioactive isotope is in all living things. When organisms die Carbon-14 decreases and can estimate how long something has been dead.
Video

14. Application of Half Life
Iodine-131, a radioactive isotope, is injected into the body to treat thyroid cancer.
It’s half life is 8 days – this tells us the rest will disappear in 80 days
Good because it will be active long enough for a cancer treatment, but should be short enough not to do more damage to healthy cells and organs.

15. Videos Alpha, Beta, Gamma http://youtu.be/5oUagoF_viQ
Alpha, Beta, Gamma
Alpha
Beta
½ life - 
Carbon dating