" After introducing some of the concepts involved in radioactive decay, I do the demonstration. Tell them that they will be flipping the penny (you will tell them when); each time they flip one half life will have passed.I usually let them keep the penny at the end of the class. If their penny lands on heads, they are radioactive and have decayed and they should sit; if their penny lands on tails, they have not decayed and may remain standing.Challenge Question (4pt Extra Credit) During World War II the United States dropped nuclear bombs on Japan.
This activity was selected for the On the Cutting Edge Reviewed Teaching Collection This activity has received positive reviews in a peer review process involving five review categories.The five categories included in the process are 75 students).The nuclear revolution, including nulcear reactors and nuclear weapons have changed the radioisotope content of the earth's surface from the constant values normally assumed in radioisotopic dating.The technique of comparing the abundance ratio of a radioactive isotope to a reference isotope to determine the age of a material is called radioactive dating.By evaluating the concentrations of all of these isotopes in a rock sample, scientists can determine what its original make-up of strontium and rubidium were.
Then, by assessing the isotope concentrations of rubidium and strontium, scientists can back-calculate to determine when the rock was formed.
The best estimate from this dating technique says the man lived between 33 BC. From the ratio, the time since the formation of the rock can be calculated.
The boat of a pharaoh was discovered in a sealed crypt and reassembled in a museum near the pyramids (see Fig. The age of our galaxy and earth also can be estimated using radioactive dating.
After each "half life", count the people remaining standing and plot it on a piece of graph paper on the overhead.
After about 3 or 4 "half-lives" ask students to predict what's going to happen to the numbers of remaining parent isotopes.
For example, strontium-86 has 38 protons and 48 neutrons, whereas strontium-87 has 38 protons and 49 neutrons.