Unit 4 Objectives By the end of this unit, you will be able to: Describe the arrangement of atoms and ions in crystalline structures Calculate formula masses for covalent and ionic compounds Explain the relation between mass, moles, and numbers of atoms or molecules, and perform calculations deriving these quantities from one another Compute the percent composition of a compound Determine the empirical formula of a compound Determine the molecular formula of a compound 2.3.0: Unit Cells 2.3.1: Unit Cells (Problems) 2.3.2: Formula Mass, Percent Composition, and the Mole 2.3.3: Formula Mass, Percent Composition, and the Mole (Problems) 2.3.4: Empirical and Molecular Formulas 2.3.5: Empirical and Molecular Formulas (Problems)