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Mr. McLeod's Notes
As isotopes radioactively decay, they do this in a specific time rate called Half life. The word means what it says, how long until 1/2 the material has decayed. So a 100g sample of an isotope with a half life of 2 hrs, will have 50g after 2hrs, 25g after 4hrs, 12.5g after 6hrs, etc. That is about it. You will only be asked these simple math questions. You can actually derivate a specific math equation to determine the amount of sample decayed in non-half life time intervals (i.e. 5hrs in the example above) but you do not need to know how to solves these problems in first year chemistry.
Notes from Section 26.4 Half Life (Addison Wesley Chemistry)
Def Half life -
Draw a rough copy of Figure 26.7 to show the amount of istope remain varies over time (in units of half lifes).
Write out the radioactive decay series in Figure 26.8 (why does the series stop??)
Read the Carbon-14 dating insert on pg766 and explain why C-14 is such a powerful age dating tool.
Look at Example 1 and then do Practice problem 10 below (pg766).