• describe/recognize the molecular structure of water. • define these terms o matter o element o atom • know and be able to define the subatomic particles found in atoms. • define atomic number and atomic mass. • be able to determine the reactivity of an element by how many electrons are in the valence shell. • distinguish between ionic, covalent, polar covalent, nonpolar covalent and hydrogen bonds. • state the difference between a compound and a molecule.