WRITING FORMULAS

                                                          Does the second word end with -ide?
                                                               yes                               no
                                                            /                                         \
                Is the second word "hydroxide"?                                          \
                    no                         yes                                                    \
                     |                              \                                                     \
 Is the first word "ammonium"?         \                                                     |
      no                        yes ---------------------------------------------->  TERTIARY COMPOUND
      
|
BINARY COMPOUND                                                                      Is the first word the name of a
                                                                                                     metal or "ammonium"?
Is the first word the name of a                                                       /                         |
nonmetal or a metal? --------->    General Rules for Writing Formulas                    1. Write "NH4+1"
       |                                     1. Write the symbol for the metal with                  2. Write symbol for the second
1. Write symbol for first                its oxidation number.                                         element with its oxidation
    element.                             2. Write the symbol for the second                          number or formula for poly-
2. Prefix of first word tells            element with its oxidation number                        atomic ion with its oxidation
    subscript of first symbol.          or formula for polyatomic ion with                        number
3. Write symbol for second          its oxidation number                                         3. Cross out the "+" and "-".
    element.                             3. Cross out the "+" and "-".                                 4. Reduce (simplify) the
4. Prefix of second word           4. Reduce (simplify) the numbers if                            numbers if possible.
    tells subscript of second           possible.                                                         5. "Criss-cross" the numbers.
    symbol.                               5. "Criss-cross" the numbers.                                    (The oxidation number of
                                                 (The oxidation number of the first                           ammonium becomes the
                                                  part becomes the subscript of the                       subscript of the second part.
                                                  second part.  The oxidation number                    The oxidation number of the
                                                  of the second part becomes the                              second part becomes the
                                                  subscript of the first part.)                                    subscript of the first part.)

--------------------------------------------------------------------------------------------------------------------------------------
EXAMPLES:
1.) calcium oxide

2.) carbon tetrachloride

3.) ammonium chromate

4.) lead (II) nitrate

5.) aluminum hydroxide

6.) iron (III) bromide

Back to the Unit 7 Notes Page

Back to the Unit 7 Page

Back to the Main Page