Inorganic nomenclature gives systematic names and formulas to inorganic compounds.

1. Basic Concepts

  • Chemical symbol: one or two letters representing an element.
  • Formula: indicates the types and numbers of atoms.
  • Valency / oxidation number: effective charge used to combine atoms in compounds.

In a neutral compound, the sum of oxidation numbers is zero:

$$ \sum (\text{oxidation numbers}) = 0 $$

For an ion, the sum equals the ionic charge.

2. Writing Formulas from Ions

To build a neutral ionic compound:

1. Write cation and anion with charges. 2. Choose subscripts so total charge is zero. 3. Simplify to the smallest whole-number ratio.

Examples:

$$ \mathrm{Na}^+ + \mathrm{Cl}^- \rightarrow \mathrm{NaCl} $$
$$ \mathrm{Ca}^{2+} + 2\mathrm{Cl}^- \rightarrow \mathrm{CaCl_2} $$
$$ 2\mathrm{Al}^{3+} + 3\mathrm{O}^{2-} \rightarrow \mathrm{Al_2O_3} $$

3. Binary Compounds

Oxides

  • Oxygen usually acts with oxidation number $-2$.
  • Name pattern: oxide of + element.

Examples:

  • $\mathrm{Na_2O}$: sodium oxide
  • $\mathrm{Fe_2O_3}$: iron(III) oxide

Hydrides

  • Hydrogen with metals usually acts as $-1$.
  • Name pattern: hydride of + metal.

Example: $\mathrm{NaH}$ sodium hydride.

4. Hydroxides (Bases)

Contain the hydroxide ion $\mathrm{OH^-}$.

General form:

$$ \mathrm{M(OH)}_n $$

Examples:

  • $\mathrm{NaOH}$: sodium hydroxide
  • $\mathrm{Ca(OH)_2}$: calcium hydroxide
  • $\mathrm{Fe(OH)_3}$: iron(III) hydroxide

5. Acids

Hydracids (binary acids)

Made of hydrogen + nonmetal (no oxygen), often in water.

Examples:

  • $\mathrm{HCl}$: hydrochloric acid
  • $\mathrm{H_2S}$: hydrosulfuric acid

Oxoacids

Contain hydrogen, oxygen, and a central nonmetal.

Examples:

  • $\mathrm{HNO_3}$: nitric acid
  • $\mathrm{H_2SO_4}$: sulfuric acid
  • $\mathrm{H_2CO_3}$: carbonic acid

6. Salts

Salts are formed by replacing hydrogen in an acid with a metal cation.

Examples:

  • $\mathrm{NaCl}$: sodium chloride
  • $\mathrm{CaCO_3}$: calcium carbonate
  • $\mathrm{KNO_3}$: potassium nitrate

7. Common Naming Systems (intro level)

  • Stock system: includes oxidation state in Roman numerals when needed.

Example: iron(II) oxide, iron(III) oxide.

  • Systematic with prefixes: mono-, di-, tri-, tetra- for atom counts.

Example: $\mathrm{CO_2}$ carbon dioxide.

  • Traditional names: used for common compounds (for example, sulfuric acid).

8. Quick Checks When Naming

1. Identify whether it is oxide, hydroxide, acid, or salt. 2. Determine oxidation number if the element has variable valency. 3. Verify charge neutrality in the formula. 4. Apply the correct naming pattern consistently.