1. List the order of events that took place: earthquake deposit D deposit B deposit G intrusive lava rocky deposit R river cuts through deposit E deposit A

3. Dating With Radioactivity  Basic Atomic Structure There are protons and neutrons in an atom’s nucleus. The number of neutrons in an atom can vary - these are called isotopes.  Radioactivity When nuclei are unstable, they break apart, or decay, in a process known as radioactivity.

4. An unstable or radioactive isotope is called a parent. The isotopes that result from the decay of the parent are called daughter products.  Half-Life A half-life is a common way of expressing the rate of radioactive decay. A half-life is the time required for one half of the atoms of a radioactive substance to decay. HALF-LIFE GRAPH

5. Number of half-lives elapsed Fraction remaini ng Percentage remainin g 0 1/11/1 100 1 1/21/2 50 2 1/41/4 25 3 1/81/8 12.5 4 1 / 16 6.25 5 1 / 32 3.125 6 1 / 64 1.563 7 1 / 128 0.781... n1/2 n 100(1/2 n )

7. Say what!?!?  A 100g sample of Millsonite has a half- life of 5 years. After 5 years - 50 grams remain After 10 years - 25 grams remain After 15 years - 12.5 grams remain After 20 years - 6.25 grams remain

8.  Radiometric Dating Radiometric dating is the procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopes.  Dating with Carbon-14 Radiocarbon dating is the method for determining age by comparing the amount of Carbon-14 to the amount of Carbon-12 in a sample.

9. So what!  Importance of Radiometric Dating Radiometric dating has been used to date thousands of events in Earth’s history. Rocks on Earth have been dated to be as much as 4 billion years old.

10. Classwork/Homework PRACTICE  Finding absolute age of a rock. BOOK p. 327  Determine D/P ratio Practice problems