Radioactive Decay with video
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Slide 1 - Radioactive DecayandRelative Age
Slide 2 - Measuring Absolute Time with Tree Rings
- Large thin walled cells form in the spring
- Smaller thicker walled cells form after the tree has leafed out
- Tree rings can be correlated based on size.
- Bristlecone pine can age back 4600 years.
Slide 4 - Measuring Absolute Time with Varves
- Varves are any sediment that shows a yearly cycle.
- In spring sands and silts run into a lake and settle to the bottom, these are thick and light in color.
- In winter, less runoff forming as a thin dark colored layer of clay.
Slide 6 - Measuring Absolute Time with Radioactive Decay
- Using radioactive elements or isotope
- These elements or isotopes give off radiation from the nuclei
Slide 7 - Radioactive Decay
- When radiation is given off the particle decays
- This makes the element lighter and changes the chemical make-up
Slide 11 - Half-Life
- Radioactive elements decay at characteristic and constant rates.
- The decay is unaffected by time, temperature, and pressure.
- The rate at which a radioactive element decays is called the half-life.
Slide 14 - -Parent Element is the Radioactive Element-Daughter Element is what the radioactive element decayed into.
Slide 17 - Problems with Radioactive Dating
- C-14 can only be used on items that were once alive.
- C-14’s half-live is very short and can not be used to date very old rocks.
- U-238 and Rb-87 is rarely found in sedimentary and metamorphic rocks.
- K-40 can be used in all three types of rocks
Slide 20 - Homework #4