Discuss and review binding energy and the nuclear strong force. Show how to indicate an element's nucleus using the symbol and atomic mass and atomic number in specific locations around the symbol. Taking iron 56 as a stable atom, indicate that atoms with atomic mass below 56, when the nucleus reacts, will form atoms with atomic mass closer to 56, while atoms above 56 will react to form nuclei also closer to 56. Show how to determine the number of neutrons from the mass and number. Discuss particle acceleration as a method of producing heavier nuclei from lighter ones. Relate how when more protons are present in an atom, more neutrons are needed to maintain stability.