Teach your students the basics of atomic structure with this Powerpoint. It will explain how to find the number of protons, neutrons, and electrons with an atom of any element, how to classify a pair of atoms as isotopes, ions, or stable atoms, and how to calculate the average atomic mass of an element.
Students can work through this Powerpoint self-paced or you can provide direct instruction. I use it to catch up my students that have never learned about the atom while reviewing with my students that have already had a year of Physical Science. There are lots of practice problems embedded in the powerpoint.