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.

Cl-1

Ca+2 Cl-1

• 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.

O-2

Al+3O-2

• 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.

• 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.

• BeF

• Li20

• B2S3

• Mg3N2

• CaCl2