Writting Formulae & Naming Compounds: Part II

In this note you will learn how to name compounds given tht formula and the reverse. You have the formula and you write the name. Then I shall deal with polyatomic ions and how to use them in names and formula.

Binary Names: Univalent Elements

Univalent elements are those metal elements that have only one allowed valence number. Some are found in column I & II on the periodic chart. Zinc, aluminum, silver, and cadmium also come to mind. Being metals the valence number represents the number of electrons that the elemnet will lose.
Lost electrons must go somewhere, they go to the nonmetals which wish to fill their outer shell.

1. So in naming the compound or writting the formula the metal atom comes first, name or formula.
2. The nonmetal comes second, name or formula. The name of the nonmetal, however must end in ....IDE.
3. Criss cross the valence values.

Binary Names: Divalent Elements

Everything listed above holds true in this case. There is just and extra step. These cations have more than one valence value. You simply have to say what it is or use the value given to you.
Iron has two valencies +2 and +3 so iron can form two different compounds, one with the +2 valence and the other with the +3 valence.
When dealing with divalent cations there is always three steps to either writting the name or the formula.

1. Name the metal or write formula with appropriate oxidation state
2. Name the nonmetal (ending in ..ide) or write the formula with appropriate oxidation state
3. then crisscross their valencies for formula , don't forget to reduce where possible.
   And when writting the name insert a Roman Numeral, between each, the valence of the metal cation.

When writing the name given the formula follow these steps:

• name the metal ion
• name the nonmetal ion making sue you end in ...IDE
• insert the correct valence value between the two names using a Roman numeral. The valence value is obtain by back criss-crossing the given numbers in the formula.
• Example:       Ni(CN)₃
  Step One: Ni is nickel
  Step Two: (CN) is cyanide
  Step Three: the number 3 croass upward to the nickel and is its oxidation state or valence value. This is the number you will insert into the name
  Finally, write the answer    nickel (III) cyanide

Chemical Nomenclature

Naming and Writing Formula of chmical compounds
This is a taught topic with board notes.

1. Binary Compounds Univalent
2. Binary Compound Divalent

If you think about this example everything should be obvious. Again, Examples are done in class.

What need here is practice; several worksheets to be given out. Just check the title with the answer sheet.

1. Quiz #2 - Ionic Compounds has answers at
2. Practice Test Binary Only has answers at
3. Formula Work Sheet 2D4 has answers at

4. Compound Names and Formulas has answers at
5. Practice Exercise Lesson 4 Review has answers at
6. Nomenclaure Test Monday September 10, 2001 has answers at
7. Molecular Compounds: has answers at
   and try my nomenclature quiz. Click on the green beaker for practice quiz Try the example then move mouse over the question to see the answer. Make sure you understand the answer and if you don't then ask for an explination.