Writing Ionic Formulas
Calcium Chloride
• Locate the metal on the periodic table and
write the element symbol with its oxidation
number.
Ca
+2
Writing Ionic Formulas
• Locate the nonmetal on the periodic table
and write the element’s symbol with its
oxidation number.
-1
Cl
+2
Ca
-1
Cl
• Find the common factor between the two oxidation
numbers.
• In this case, 2.
• Decide how many of each ion is needed to make
the charge equal to the common factor.
• In this case, 1 calcium ion (+2) and 2 chlorine ions
(-1 and –1 = -2). Compounds are neutral.
• Use this number of ions as the subscript for the
element, and write the formula.
• In this case, Ca Cl2.
Writing Ionic Formulas Part 2
Aluminum Oxide
• Locate the metal on the periodic table and
write the element symbol with its oxidation
number.
Al
+3
Writing Ionic Formulas Part 2
• Locate the nonmetal on the periodic table
and write the element’s symbol with its
oxidation number.
-2
O
+3
Al
-2
O
• Find the common factor between the two oxidation
numbers.
• In this case, 6.
• Decide how many of each ion is needed to make
the charge equal to the common factor.
• In this case, 2 aluminum ions (+3 and +3 = +6) and
3 oxygen ions (-2 and -2 and -2 = -6). Compounds
are neutral.
• Use this number of ions as the subscript for the
element, and write the formula.
• In this case, Al2O3.
Try these examples on your own.
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Sodium and Oxygen
Lithium and Sulfur
Aluminum and Chlorine
Potassium and Nitrogen
Magnesium and Fluorine
Naming Ionic Compounds
• Write the name of the metal.
• Write the name of the nonmetal with the ending
changed to –ide.
Example:
Nitrogen = nitride
Sulfur = sulfide
Oxygen = oxide
Chlorine = chloride
Phosphorus = phosphide
Iodine = iodide
Fluorine = fluoride
Bromine = bromide
Naming Ionic Compounds
Al2S3
• Write the name of the metal.
Aluminum
• Write the name of the nonmetal, changing
the ending to –ide.
Sulfide
• Name the compound.
Aluminum Sulfide
Naming Ionic Compounds
BaCl2
• Write the name of the metal.
Barium
• Write the name of the nonmetal, changing
the ending to –ide.
Chloride
• Name the compound.
Barium Chloride
Try these examples on your own.
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BeF
Li20
B2S3
Mg3N2
CaCl2