Chemical Formulas and Equations

Back To Erik's Chemistry: Main Page

Review Material, AP Chemistry
  1. Prediction of formulas of ionic compounds
    1. Charges of monatomic ions of main group elements can be predicted from position in Periodic Table.
    2. Transition metal cations can have multiple charges. You must know the common transition metals.
      (Table 2.4 page 62)
    3. Polyatomic ions; know common ions, hand out.

  2. Names of compounds
    1. Ionic Compounds: give name of cation followed by that of anion (ends in -ide). If metal forms more than one cation, as with many transition metals, then names of ions have suffixes that are related to their ionic charges: -ous refers to the lower charge: -ic refers to the higher charge.

      **The IUPAC (Stock Name) system uses Roman Numerals.**

    2. Names of polyatomic ions containing oxygen- some elements form several polyatomic ions with oxygen. A series of suffixes and prefixes is used to specify the relative number of oxygen atoms.
      per-........-ategreatest number of oxygen atoms
      hypo-........-itesmallest number of oxygen atoms
      The mercurous ion is an exceptional case, it requires special attention. The formula and charge for the mercurous or mercury (I) ion is Hg2+2. Note that this ion contains two mercury atoms.

    3. Binary molecular compounds (two nonmetals)
      Indicate number of atoms of each element using greek prefixes (page 67).

  3. Acid nomenclature

    Acids- Acids are molecular compounds that contain hydrogen bonded to a nonmetal to a group of atoms that behave like a nonmetal. Acids can be either binary or ternary compounds. The names of binary acids have the form Hydro-........-ic acids. The names of ternary acids use a series of prefixes and suffixes to specify the relative number of oxygen atoms in the molecule.

    per-........-icgreatest number of oxygen atoms
    hypo-........-oussmallest number of oxygen atoms

    If only two different ternary acids exist for a given nonmetal, only the suffixes -ic and -ous are used.

    HClO4perchloric acid
    HClO3chloric acid
    HClO2chlorous acid
    HClOhypochlorous acid

back to top
Back To Erik's Chemistry: Main Page

Any comments will be appreciated. Please e-mail me at

This page was made by Erik Epp.