These exercises are organized into two types, 1) writing formulae and naming them given ions or molecules, and 2) writing formulae given chemical names.
Note that formulae are generally written with the elements ordered by electronegativity (roughly, elements on the left side of the Periodic table precede those on the right).
You should know about the Stock system of nomenclature for cations and ionic compounds.
- For cations with a single oxidation state (Type I) the name of the element is the name of the cation (no Roman numeral is necessary)
- For cations with more than one oxidation state or charge (Type II) the oxidation number of a cation is indicated by Roman numerals in parenthesis following the symbol with no space, e.g. Fe(III), and the name is then the element name plus the number Fe(III) = iron three = iron(III).
(Examples 1-10 are answered with explanations, a-j are provided for extra practice - answers only are given.)
F- a. Na+ OH- 2. Al3+ S2- b. Ga3+ PO43- 3. NH4+ CN- c. Cu2+ HCO3- 4. Hg22+ C2H3O2- d. Fe2+ CrO42- 5. Pb2+ SO42- e. Pb4+ NO3- 6. Sn4+ Cr2O72- f. Hg22+ I- 7. H+ SO42- g. H+ PO33- 8. H+ ClO4- h. H+ NO3- 9. Cs+ NO2- i. Rb+ OH- 10. Ba2+ O22- j. Sr2+ O2-
Note that you can guess the charge on most elemental ions based on their positions on the Periodic table.
In addition to these exercises you should familiarize yourself with the text materials and with the Department web pages linked below.
© R A Paselk
Last modified 10 September 2009