1. Benefits & Dangers of: Radioisotopes

2. Dating (not that kind)
C-14 used to date organic (previously living) materials
living organisms incorporate C-14 into their structure, along with C-12
C-14 decays with known half-life
146C  147N 
comparing ratios of 14C: 12C
figure how many half-lives gone by since died
helps determine age of substance

3. ROCKS U-238 decays to Pb-206 (manysteps)
over time: amount U  & amount Pb 
- scientists compare ratio of U-238 to Pb-206
to date rocks

4. Chemical Tracers
detect radioactive materials & decay products
tracer: radioisotope used to follow path of material in system
P-31: determines P uptake in plants
C-14: maps C in metabolic processes
C-14: maps organic molecules & figures out reaction mechanisms

5. Industrial Applications
tracers kill bacteria and spores in food and mail
Medical Applications
Co-60 & Cs-137: destroys anthrax bacilli
Co-60: kills bacteria in foods
Tc-99: treatment of brain cancer

6. Medical Applications
radioisotopes with short half-lives (quickly eliminated from body)
for medical diagnosis
diagnose & treat cancers
I-131: diagnosis & treat thyroid disorders
Co-60: gamma emitter
used to kill cancerous tumors

7. Power Plants radioactivity used as fuel source to generate electricity
advantages:
no contributions to greenhouse gases
no mercury contamination of atmosphere

8. Radiation Risks damage normal tissue
high doses can cause illness & death
cause DNA mutations
disposal of waste is difficult
especially from nuclear power plants
fuel rods are mix of many radioactive substances
storage & transportation both problematic