WARM-UP 1/31/08 – 2/1/08

1. In which type of rock are fossils most likely to be found? Igneous intrusive Igneous extrusive Sedimentary Metamorphic

3. Which of the following most likely results in the formation of a fossil? A Mesozoic clam lies exposed on the surface of the sea floor. A Mesozoic clam is washed up onto the beach. A Mesozoic clam is eaten by a large predatory fish. A Mesozoic clam is buried by a mudslide

Half-Life

Half-life The time required for half of the nuclei in a sample of a specific isotope to undergo radioactive decay. The half-life for a given isotope is always the same ; it doesn't depend on how many atoms you have or on how long they've been sitting around.

M&M LAB Get in groups of four Clear off the desk except for pen/pencil a sheet of paper a paper towel A cup of M&M’s A “Safe”cup

Determining the Half-life of M&Mium Purpose: To determine the half-life of the element M&Mium. Important: DO NOT EAT ANYTHING!!!!! (Unless Ms. Mericle says its okay)

Determining the Half-life of M&Mium Procedure: Mark 1 cup “Safe”. This is for the discarded “M&M’s” Count the number of M&Mium atoms as you place them in the cup. Record the total number of radioactive atoms you start with in your data table. Cover and shake/rattle the cup. Carefully pour your atoms onto your white paper.

Determining the Half-life of M&Mium *** You will see that several of the previously radioactive atoms in the group have decayed (safe), and the m is no longer visible As you remove the safe atoms, count them so you may determine the number of atoms that have decayed in that particular shake (Place “safe” atoms in marked cup)

Determining the Half-life of M&Mium Continue until no more radioactive members remain. *** Remember to record the number of decayed atoms after each shake! *** Conclusion: Calculate the half-life of M&Mium? (i.e., What number of shakes are necessary to reduce the radioactive members to one-half?)

Your graph should look something like this.