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Chapter 3

Chemical Compounds

Shaun Williams, PhD

Ionic and Molecular Compounds

Electrolytes and Nonelectrolytes

Strong and Weak Electrolytes

Molecular View of Electrolytes and Nonelectrolytes

A pictures showing electrolytes dissociated into ions in water allowing the solution to conduct electricity while nonelectrolytes do not dissociate nor do they allow the solution to conduct electricity.

Ionic Compounds

Molecular View of Ionic Compounds

An image showing salt in its solid, crystalline form and salt dissociated in water.

Molecular Compounds

  • Are composed of 2 or more nonmetals
  • Have no overall charge
  • Are the other major category of chemical compounds
An image showing crystalline salt along with a molecule of carbon dioxide and a molecule of oxygen.

Ionic and Molecular Compound Properties

Properties of Ionic and Molecular Compounds
Ionic Compounds Molecular Compounds
Crystalline solid Gas, liquid, or solid
Hard, brittle solid Soft solid
Very high melting point Low melting point
Very high boiling point Low boiling point
High density Low density
Strong electrolyte in aqueous solution Weak or nonelectrolyte in aqueous solution
Electrical conductivity is good when compound is molten Electrical conductivity is poor in pure form

Monatomic and Polyatomic Ions

Monoatomic Ions

A image of the outline of the Periodic Table with monatomic ions indicated.

Polyatomic Ions

A table of some of the polyatomic ions.

Important Polyatomic Anions

Ions with a \(1-\) charge Ions with a \(2-\) charge
Nitrate \(\chem{NO_3^-}\) Chromate \(\chem{CrO_4^{2-}}\)
Nitrite \(\chem{NO_2^-}\) Dichromate \(\chem{Cr_2O_7^{2-}}\)
Bicarbonate \(\chem{HCO_3^-}\) Sulfate \(\chem{SO_4^{2-}}\)
Perchlorate \(\chem{ClO_4^-}\) Sulfite \(\chem{SO_3^{2-}}\)
Chlorate \(\chem{ClO_3^-}\) Carbonate \(\chem{CO_3^{2-}}\)
Chlorite \(\chem{ClO_2^-}\) Oxalate \(\chem{C_2O_4^{2-}}\)
Hypochlorite \(\chem{ClO^-}\) Peroxide \(\chem{O_2^{2-}}\)
Cyanide \(\chem{CN^-}\) Ions with a \(3-\) charge
Hydroxide \(\chem{OH^-}\) Phosphate \(\chem{PO_4^{3-}}\)
Acetate \(\chem{C_2H_3O_2^-}\) Phosphite \(\chem{PO_3^{3-}}\)
Permanganate \(\chem{MnO_4^-}\) Borate \(\chem{BO_3^{2-}}\)

Formulas for Ionic Compounds

Writing Formulas for Ionic Compounds

An example of various ionic compounds.

Naming Ionic Compounds

How to name ionic compounds

Summary of Main Group Metals

The outline of the Periodic Table with some cation charges overlayed.

How to finish naming ionic compounds

Summary of Naming with Transition Metals

A flow chart of naming ionic compounds.

Naming and Writing Formulas for Molecular Compounds

Naming Molecular Compounds

Common Greek Prefixes

Prefix Name Prefix Name
mono- 1 hexa- 6
di- 2 hepta- 7
tri- 3 octa- 8
tetra- 4 nona- 9
penta- 5 deca- 10

Summary of Naming Molecular Compounds

A flow chart of naming molecular compounds.

Acids and Bases

What are acids and bases?

  • Acids
    • Are substances that when dissolved in water provide hydrogen ions (\(\chem{H^+}\))
    • An example of the dissociation (or ionization) of an acid: \[ \chem{HCl(aq) \xrightarrow{H_2O} H^+ (aq) + Cl^- (aq)} \]
  • Bases
    • Are substances that react with acids in aqueous solution to form water
    • An example of the ionization of a base: \[ \chem{NaOH(s) \xrightarrow{H_2O} Na^+(aq) + OH^-(aq)} \]
A picture showing dissolving hydrogen chloride gas into water to make hydrochloric acid.

Names of Some Common Acids

Formula Name Formula Name
\(\chem{HF(aq)}\) Hydrofluoric acid \(\chem{H_2SO_4(aq)}\) Sulfuric acid
\(\chem{HCl(aq)}\) Hydrochloric acid \(\chem{H_2SO_3(aq)}\) Sulfurous acid
\(\chem{HI(aq)}\) Hydroiodic acid \(\chem{HClO_4(aq)}\) Perchloric acid
\(\chem{H_2S(aq)}\) Hydrosulfuric acid \(\chem{HClO_3(aq)}\) Chloric acid
\(\chem{H_2CO_3(aq)}\) Carbonic acid \(\chem{HClO_2(aq)}\) Chlorous acid
\(\chem{HNO_3(aq)}\) Nitric acid \(\chem{HClO(aq)}\) Hypochlorous acid

Naming Acids

Summary of Naming Acids

A flow chart of naming acids.

Summary of Naming Compounds

A flow chart of naming compounds.

A General Summary of Naming Compounds

Type of Compound Naming
Ionic Cation named first followed by anion
Molecular 1st atom in formula (the element farther down or to the left in the periodic table) named 1st with the second element named as if it were an anion. Greek prefixes are used to designate the number of atoms in a molecule.
Acids Binary acids are named as hydro- followed by the root of the element name with an –ic suffix and the word acid placed at the end of the name. Acids containing polyatomic ions are named by taking the root of the polyatomic ion name, replacing –ate with –ic or replacing –ite with –ous and adding the word acid at the end.