1. Absolute Dating
Write on right side

2. Review of Atoms Atoms are the smallest unit of matter.
Atoms have 3 parts:
Proton: positively charged (in the atom’s nucleus)
Neutron: no charge (in the atom’s nucleus)
Electron: negatively charged (orbit around the nucleus)
Atoms of the same element can have a different number of neutrons, we call these isotopes.

3. Absolute Dating
Absolute dating: determining the actual age of an event or object in years
One method of absolute dating is radioactive decay: the breakdown of a radioactive (unstable) isotope into a stable isotope
Each isotope decays at a certain rate. Half-life is the time needed for half of a substance to undergo radioactive decay to form daughter isotopes

4. Radiometric Dating
Radiometric Dating: finding the absolute age (how old something is in years) by determining the percent of parent and daughter isotope
This is the most accurate way to measure a rock’s age

5. Radiometric Dating Continued
Radiocarbon Dating: determining age by measuring amount of Carbon-14
Half-life of Carbon-14 is 5, 730 years
Other types of radiometric dating: potassium-argon dating (potassium-40 decays into argon) and uranium-lead dating (uranium-238 decays into lead-206)
Note: As Uranium-238 decays, the amount of uranium DECREASES and the amount of lead-206 INCREASES

6. Index Fossils
Some fossils can be used to determine the age of the rock where it is found, we call these index fossils

7. Reflection (Left Side)
On page 186 in your textbook, answer questions #17 &18 (look at pg 184 for answers).
Cut out and glue/tape in your journals on the left side.