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Absolute Dating

Absolute Dating

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Absolute Dating

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Presentation Transcript

  1. Absolute Dating Chapter 3, Sec.3

  2. Process to find the approximate age of rocks or fossils

  3. Atoms • Smallest part of matter • Made of protons, neutrons, electrons • Center called the nucleus

  4. Everything is made of atoms

  5. Protons, neutrons in nucleus • Electrons move around nucleus

  6. Every element has a diff. # of protons

  7. Isotopes • Atoms of the same element with different # of neutrons

  8. Radioactive Decay • Most atoms are stable • Some are unstable and breakdown or decay (radioactive)

  9. High energy particles are given off • Can damage cells, organs, etc.. • X-rays, gamma rays, electrons, protons, neutrons

  10. Decay occurs at a constant rate called half-life

  11. Half-life • The time it takes for one-half of a sample to decay

  12. Problem • I start with 10 grams of a sample • It’s half-life is 20 years • After 20 years, how much left? • After 40 years, how much left 5 grams 2.5 grams

  13. Some unstable isotopes decay into stable isotopes

  14. 3 radioactive dating methods • Uranium-Lead Method • Potassium-Argon Method • Carbon-14 Method