How to write the chemical formula and chemical names of ionic compounds
is a combination of symbols that represent a particular compound
shows the combining ratio of atoms
Writing Chemical Formulas:
Example 1: what is the formula for the ionic compound formed by calcium and iodine?
STEP 1: Write the symbols, with the metal first.
STEP 2: Write the ionic charge above each symbol to indicate the stable ion that each
STEP 3: Determine how many ions of each type you need so that the total ionic charge is
_____(+2) + ____ (-1) = 0
1 (+2) +
2 (-1) = 0
(+2) + (-2)
STEP 4: Write the formula using subscripts to indicate the number of ions of each type.
*NOTE: the subscript “1” is unnecessary because the symbol
itself represents ONE atom/ion
Writing chemical names:
Always remember, the metal keeps its name, and the non-metal needs the ending (suffix) to be
changed to “–ide”.
Using the example above, the chemical name of CaI
is Calcium iodide.