Apologia Chemistry: Empirical Formulas and Isotopes or Beanium

Today, we reviewed Percent Composition with coins and empirical formulas.  I'm going to use the coins for several examples of empirical formulas next week and until I think the kids are gaining an understanding of empirical formulas.  We began with three quarters (5.7 g each) , two dimes (2.3 g), and one nickel (5.0g).  I walked the kids through the steps to converts the coins into percents by mass, then to convert the percents into moles, and finally how to compare the mole ratios back to the original empirical formula.  I plan to do several similar examples with compounds and coins next week to drive home the concept.

Then the kids did Beanium.  We discussed what an isotope is.  The reason I introduce isotopes and Beanium now is the kids are learning about percent composition in terms of empirical formulas.  Don't ask me why; I've learned that calculating weighted averages for an isotope in Beanium makes sense to the kids now when they are learning about empirical formulas.  I don't know of a good time to learn about isotopes.  The main point to Beanium is that all of the different types of beans are isotopes for the element, Beanium.  The kids submit neat lab tables and a definition of isotopes in their own words.  We spent time in class with talking about C-12, C-13, and C-14, their relative abundance in terms of the atomic mass.  I mentioned that C-14 forms in the upper atmosphere.  Next week, I want to assign Otzi the Iceman and Carbon dating.  The kids aren't ready for empirical formulas homework; I gave them an article to read, Feeding the World.  The kids are writing a summary paragraph.  Chemmatters are articles published by the American Chemical Society for high school students.  ACS has teacher's guides with background, questions, and lesson ideas.

Below are photos from class.  I'm trying to remember to take photos of the board as we work.  The Beanium photos are just evidence we actually do the labs cited here.