describe how and why the atomic model has changed over time

the models of Dalton, Thomson, Rutherford, Bohr, Geiger and Marsden

describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with most of the mass in the nucleus

recall the typical size (order of magnitude) of atoms and small molecules

the concept that typical atomic radii and bond length are in the order of 10^–10 m

recall relative charges and approximate relative masses of protons, neutrons and electrons

calculate numbers of protons, neutrons and electrons in atoms and ions, given atomic number and mass number of isotopes

definitions of an ion, atomic number, mass number and an isotope, also the standard notation to represent these