1. Pinpointing Time
C1.5

2. What is Radioactivity?
Marie Currie discovered radioactivity – the emission of energy from the nuclei of unstable atoms as the change to become more stable.
Radioactive decay – the breaking down of the nuclei into a stable nuclei and particles
Half-life – time it takes for half of the original nuclei (parent) to break into the stable nuclei (daughter).
Mass spectrometer – instrument used to detect the amount of atoms present in a sample

3. Ernest Rutherford Rutherford built on the work of Marie Curie
He found that radon-220 was unstable and spontaneously changed into polonium.
As it changed it released energy
When we discuss radioactivity we often refer to two isotopes are often referred to:
Original unstable atom called the parent isotope
More stable product called the daughter isotope

4. What Is Radioactive Dating
Scientists can use radioactive elements and decay curve to predict the date of a sample. (pg 8 of your databook or pg. 557 of the text)
Write out the decay reaction using pg 8. Parent  Daughter + particles + energy
If necessary determine the percentage of parent remaining by subtracting from 100
Use the decay curve to determine the half-lives
Multiple the half-lives by the years in one half life (pg. 8) to determine the absolute age
Absolute age = half lives x years/one half life

5. An Example of Finding an Age
A zircon rock has 30% of lead 206
U 

6. Constructing A Decay Curve
Pg. 320

7. Assignment Add the dates to your timeline
Practice Questions  Do these!
1.5 Questions
Pg. 324 #1-6
C1.0 Quiz  Tomorrow