Naming Molecules Section 9.2

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Naming MoleculesSection 9.2

• Chemistry

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Objectives

• Identify the names of binary molecular compounds
  from their formulas.

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Analogies

• The millions of compounds in the world and
  crayons in the Crayola box

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Naming Binary Molecular Compounds

• binary a molecule that contains only two
  different elements.
• do not contain metals or ions
• Do contain two different nonmetals

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3 Rules for Naming Binary Compounds

• The first element in the formula is always named
  first, using the entire element name.
• The second element in the formula is named using
  the root of the element and adding the suffix
  ide.

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3 Rules for Naming Binary Compounds Cont.

• Prefixes are used to indicate the number of atoms
  of each type that are present in the compound.
• Prefixes are similar to the ones used in geometry
  in naming polygons.

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Prefixes for Molecular Compounds
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2

• One mono-
• Two di-
• Three tri-
• Four tetra-
• Five penta-

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4
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Prefixes for Molecular Compounds Cont.
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• Six hexa-
• Seven hepta-
• Eight octa-
• Nine nona-
• Ten deca-

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Prefixes for Molecular Compounds Cont.

• One exception is that the first element in the
  formula never uses the prefix mono-.
• Ex CO
• Incorrect Monocarbon monooxide.
• Correct Carbon monooxide.

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Example Problems

• Page 249
• 13-17

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Common Names of Compounds

• Many binary compounds were discovered and given
  common names long before the modern naming system
  was developed.
• Examples Page 249, table 9-2.

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Formulas and Names of Some Covalent Compounds
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Naming Acid

• Water solutions of some molecules are acidic and
  are named as acids
• If the compound produces hydrogen ions in
  solution, it is an acid.

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Naming Binary Acids

• A Binary Acid contains hydrogen and another
  element.
• When naming a binary acid , use the prefix hydro-
  to name the hydrogen part of the compound,
• The second element use the root name and the
  suffix -ic.
• Example HBr

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Naming Oxyacids

• Any acid that contains hydrogen and an oxyanion
  is referred to as a oxyacid.
• Remember an oxyanion is a polyatomic ion that
  contains an oxygen atom

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Rules for Naming Oxyacids

• Name depends on the oxyanion present
• The name of an oxyacid consists of a form of the
  root of the anion, a suffix , and the word acid
• If the oxyanion ends in ate , it is replaced by
  ic
• If the oxyanion ends in ite, it is replaced by
  ous

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Examples

• HNO3
• HNO2

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Practice Problems

• Page 250

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Writing Formulas from Names

• Subscripts are determined by prefixes
• Example Dihydrogen monoxide

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Homework

• 23-29 on page 251