Chapter 7: Chemical Formulas and
Chemical Compounds
Section 1:
Chemical Names and Formulas
Overview
• We will explain the significance of a chemical formula.
• We will again look at how to determine the formula unit
of an ionic compound.
• We will name an ionic compound based on its formula
unit.
• We will use prefixes to name binary molecular
compounds based on its formula.
• We will write the name of a binary molecular compound
based on its name.
Significance of Formulas
• A chemical formula indicates what elements there are in
the compound.
• It also says by the subscripts how many atoms of that
element are needed.
• Fe2O3 – 2 Iron Atoms, 3 Oxygen Atoms
• Al2(SO4)3 – 2 Aluminum Atoms, 3 Sulfur Atoms, and 12
Oxygen Atoms
• Nomenclature – A naming system.
Naming Monatomic Ions
• Monatomic ions are made of only one charged
atom.
• Naming Cations
• Barium → Barium cation or Barium ion
• Cesium → Cesium cation or Cesium ion
• Naming Anions
• Sulfur → Sulfide anion or Sulfide ion
• Oxygen → Oxide anion or Oxide ion
Naming Binary Ionic Compounds
• If needed, solve for the formula unit. (pg 222)
• Naming the formula unit: Al2O3
• Aluminum Oxide
• Work it backward: Iron (II) Oxide
• FeO
• Stock system of nomenclature: Al2O3
• Aluminum (III) Oxide
Naming Polyatomic Ion Compounds
• Naming Polyatomic ion compounds: Al(NO3)3
• Aluminum Nitrate
• Aluminum (III) Nitrate
• See page 226 or your Mastery Manual for a list of
Polyatomic ions and their names.
• Oxyanions – Anions that contain oxygens.
Naming Binary Molecular Compounds
• See Table 7-3 on page 228 for a list of prefixes.
• This nomenclature is for covalent compounds
only, not for ionic compounds.
• Still use the –ide suffix for nonmetals.
• H2O
• Dihydrogen oxide
• Carbon tetrachloride
• CCl4
Naming Acids
• See table 7-5 on page 230 for a list of common
acids and their names.
• Salt – An ionic compound made of a cation and
anion that formed from and acid-base reaction.
• Most common:
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•
•
•
H2SO4 – Sulfuric Acid
HNO3 – Nitric Acid
HCl – Hydrochloric Acid
CH3COOH – Acetic Acid