Electron Shells

Finally, a hands-on activity! After all the problems with the abstract nature of atomic theory, I was concerned about what would happen when I started doing ionic & covalent bonding, electron shells, etc. Honestly, I might have skipped electron shells altogether if I hadn't found some nice hands-on activities at Middle School Science. Today, I made a handout which showed the different energy levels of an atom and the number of electrons which can "fit" at each energy level. Then the kids used pennies as "electrons" and figured out how many electrons go in each shell for atoms of different elements. This lays the groundwork quite nicely to understand how ionic and covalent bonds form, and the kids really seemed to get it. Yay! They also picked up electron dot diagramming fairly quickly, though I fear that it may lead to some confusion about the number of electrons in an atom versus the number of electrons in the outer shell.

A few days ago, the kids asked why the protons in the nucleus don't repel each other - an excellent question - and I found the answer for them: They are held together by "the strong force." Um, sure. Sometimes physical science sounds like voodoo or wizardry.