NDSU Chem 121 Exam 2 With Complete Solution

NDSU Ch em 121 Exam 2 With Compl ete Solution Chemical formulas - ANSWER denote elements in a substance by chemical symbols and the ratios in which the atoms are combined by subscripts molecular formula - ANSWER a chemical formula that denotes the exact number of atoms of each element in molecule examples of a molecular formula - ANSWER H2O, NH3, CH4, C2H6, C6H6 empirical formula - ANSWER gives the smallest whole number ratio of atoms of each element in a compound examples of empirical formula - ANSWER CH, CH2, CH4, N2O5 Structural formula - ANSWER shows which atoms are connected (chemically bonded) together. Structural formula examples - ANSWER H2O, H2O2, CO2 Polyatomic ions - ANSWER ions that consist atoms chemically bonded together in a molecular sense and carry a net charge (positive or negative) polyatomic ions examples - ANSWER NO3-, SO4(2-), PO4 (3-), CO3(2-), NH4+ Ionic compounds - ANSWER composed of cations and anions interacting in appropriate proportions to yield an overall neutral compound ionic compound examples - ANSWER common table salt chemical formulas of ionic compounds - ANSWER formulas represent the smallest whole number ratio of the ions in the compound (empirical formula) writing formulas for ionic compounds - ANSWER 1. ionic compounds are always neutral 2. cation is always written first then anion 3. subscripts denote number of ions of each type required to yield a neutral compound (smallest whole number ratio) referred to as a formula unit Formation of an ionic compound - ANSWER for charge balance, the subscript