Announcements

1
Announcements

• To join clicker to class today
• Turn on the Clicker (the red LED comes on).
• Push Join button followed by 20 followed by
  the Send button (switches to flashing green LED
  if successful).

• Some still need to sign up for e-mail discussion
  listinstructions in syllabus.
• Quiz 2, Monday (sections 1.6-2.8).

• Exam 1Chapters 1 2 Wednesday.
• Download handout for next week's labDo prelab
  pages.

2
Review

• Fusion in stars producing elements larger than H
  and He.
• H fusion to get He in stars like our sun.
• Multiple fusions in larger stars. Ends at 5626Fe
• Radioactive decay
• above band of stability undergo ß-decay
• below undergo e--capture or e-emission, beyond
  undergo a-decay.
• Can get to Bi by n-capture and ß-decay.
• Heavier than Bi, produced by rapid n-capture in
  supernovas.
• Common kinds of radioactive decay a and fission.

3
Radioactive Dating

• Expression for fraction left at time, t
• Solving for t t t1/21/ln(0.5)ln(At/Ao)
• Carbon Dating
• Use 14C/12C ratio for At and Ao
• Use new sample to get Ao
• Other isotopes Aostable product remaining
  radionuclide At remaining radionuclide.