Naming Compounds and Formulas

Naming Ionic Compounds

• When naming ionic compounds, the cation’s name always comes before the name of the anion

– Sodium (+1) Chloride (-1)

Naming Ionic Compounds

• Use the symbol of the cation first, followed by the elemental symbol for the anion

• Use subscripts to show the ratio of the ions in the compound

– Sodium Sulfide = (Na2S)

• In the bonding of an Ionic compound, the anion’s name will always end in an –ide

Examples: Sodium Chloride and Magnesium Oxide

Metals with Multiple Ions

• Some transition metals will form more than one ion– Some form one ion and some form 2 or 3 ions

• We use roman numerals to indicate the charge of the ion– Iron (III) has a charge of +3

Metals with Multiple Ions

CuO

In this compound containing copper we can figure out that the copper being used is copper(II) because 2 positive charges are needed to neutralize oxygen’s -2 charge

Rules for Naming Covalent Compounds

• The element that appears most “left” on the periodic table appears first in the compound name

• Example: Hydrogen Chloride

• If you have more than one atom of an element, we use prefixes to name them

We usually DO NOT include the mono- prefix in the first element

• For Example:

– Dihydrogen Monoxide • 2 Hydrogen and 1 Oxygen

We also add the ending –ide to bonds including two non-metals (all covalent bonds)

Example: Carbon Monoxide