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Introduction to Absolute (Radiometric) Dating. Learning Targets 4a) I can distinguish between absolute and relative dating. (DOK 1) 4b) I can define what.

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Presentation on theme: "Introduction to Absolute (Radiometric) Dating. Learning Targets 4a) I can distinguish between absolute and relative dating. (DOK 1) 4b) I can define what."— Presentation transcript:

1 Introduction to Absolute (Radiometric) Dating

2 Learning Targets 4a) I can distinguish between absolute and relative dating. (DOK 1) 4b) I can define what an isotope is and describe how radioactive isotopes decay (DOK 1) 4e) I can identify and analyze key strengths and limitations of using radioactive decay in absolute dating. (DOK 1-2) Essential Question How do scientists use absolute dating to build a model of the Earth’s history?

3 Absolute Dating

4 Isotopes Two or more of the same element with different masses. Have the same number of protons but number of neutrons changes.

5 Isotopes

6 Radioactivity o Some atoms are not stable o These atoms emit particles to achieve stability

7 Radioactivity There are three types of particles emitted: 1.Alpha particles 2.Beta Particles 3.Gamma Rays

8 Alpha Particles o Charge = +2 (2 protons) o Mass = 4 (2 protons + 2 neutrons) o Large, easily stopped by paper © The Geological Society of America, 2003

9 Beta Particles o Charge = -1 o Mass = negligible o Small, more penetrating particle, but still easily stopped

10 Beta Particles o Neutron decays into a proton and an electron o Electron leaves o Atomic number goes up 1

11 Gamma Rays o Pure energy o No change in atom o Very penetrating, cause damage

12 Absolute (Radiometric) Dating o Based on decay rates of different atoms o Rate of decay stated as half-life

13 Half-Life Time it takes for ½ of the radioactive atoms to decay into its daughter atoms © The Geological Society of America, 2003

14 Half-Life Atoms used in geologic dating have long half- lives ParentDaughterHalf-Life Uranium-238Lead-2064,470 million years Uranium-235Lead million years Potassium-40Argon-401,250 million years Rubidium-87Strontium-8748,800 m. y. Carbon-14Nitrogen-145,730 years

15 Half-Life Scientists use both decay and production curves © The Geological Society of America, 2003

16 Assigning Ages Using the proportion of daughter atom in a sample, its age can be determined

17 Major Principle of Absolute Dating

18 Check for Understanding Explain the main concepts of how scientists use absolute (radiometric) dating to determine the age of objects


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