25.6 Radioactive decay

• The time since an organism dies can be determined by comparing the activities or the ratios of carbon-14 to carbon-12 nuclei.
• Carbon-14 has a half life of 5730 years.
• Limitations to carbon dating are, it assumes that the ratio of carbon-14 to carbon-12 atoms has remained constant over time; increased emission of carbon dioxide from burning fossil fuels may have reduced this ratio.
• Other limitations of carbon dating are solar flares from the sun and by the testing of nuclear bombs.
• You can not use carbon-14 to date rocks on the Earth or meteors formed during the solar system's formation, because it's half life is not long enough for these ages, instead geologists use the decay of rubidium-87 as it's half life is 49 billion years old.