Isotopes
- Created by: Jadii
- Created on: 11-11-13 20:22
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- Isotopes
- Atoms of the same element which have different mass numbers (different number of neutrons)
- Relative Isotopic Masses
- Take abundances into account
- Cl-35 and Cl-37
- 75% and 25%
- Cl-35 and Cl-37
- (35x75) + (37x25) / 100 = 35.5
- Take abundances into account
- Half-life of radioisotope carbon-14 is 5730 years
- After two half -lives it will be 25% of the original count rate
- As 1 half-life is 5730 years, the time taken for the radioisotope to decay to 25% of its original value is 2 x 5730 years = 11460 years
- After two half -lives it will be 25% of the original count rate
- A cautionary note
- For radiometric systems to work as geological clocks there are some criteria that must be fulfilled:
- The half-life of the radioisotope must be known accurately
- There must have been no movement of either parent or daughter isotopes out or into a mineral since the time of crystaliiation of the rock
- There must have been no resetting of the radiometric clock - heating and deformation of rocks
- For radiometric systems to work as geological clocks there are some criteria that must be fulfilled:
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