Chemistry: Naming Ionic and Covalent Compounds

Study Notes

Naming Ionic Compounds

Ionic compounds are formed by the electrostatic attraction between positively charged cations and negatively charged anions.
Cations are formed when a metal loses electrons, and anions are formed when a nonmetal gains electrons.
The name of the cation is usually the same as the element name (e.g., sodium, magnesium).
The name of the anion is derived from the element name, but typically ends in "-ide" (e.g., chloride, oxide).
To name an ionic compound, write the name of the cation followed by the name of the anion.
Examples:
- NaCl (sodium chloride)
- MgO (magnesium oxide)
- KBr (potassium bromide)

Naming Covalent Compounds

Covalent compounds are formed by the sharing of electrons between nonmetal atoms.
When naming covalent compounds, prefixes are used to indicate the number of atoms of each element present in the molecule.
The prefix "mono-" is used for one atom, "di-" for two, "tri-" for three, "tetra-" for four, "penta-" for five, "hexa-" for six, etc.
The first element in the formula is named first, and the second element is named with its root and the suffix "-ide".
Examples:
- CO (carbon monoxide)
- CO₂ (carbon dioxide)
- N₂O₄ (dinitrogen tetroxide)
- PCl₃ (phosphorus trichloride)

Transition Metal Cations

Transition metals can form more than one cationic charge.
Roman numerals are used in parenthesis to indicate the charge of the metal cation.
Examples:
- FeCl₂ (Iron(II) chloride)
- FeCl₃ (Iron(III) chloride)
- Cu₂O (Copper(I) oxide)
- CuO (Copper(II) oxide)

Polyatomic Ions

Polyatomic ions are charged groups of covalently bonded atoms.
These groups must be memorized.
Examples include:
- Nitrate (NO₃^-)
- Sulfate (SO₄^2-)
- Phosphate (PO₄^3-)
- Carbonate (CO₃^2-)
- Hydroxide (OH^-)
- Ammonium (NH₄⁺)
Naming ionic compounds containing polyatomic ions involves naming the cation, followed by the polyatomic ion.
Examples:
- NaNO₃ (sodium nitrate)
- K₂SO₄ (potassium sulfate)
- Ca₃(PO₄)₂ (calcium phosphate)
- (NH₄)₂CO₃ (ammonium carbonate)

Acid Naming

Acids are compounds that release hydrogen ions (H⁺) when dissolved in water.
Naming binary acids (those containing hydrogen and one other nonmetal) involves using the prefix hydro- followed by the root of the nonmetal name, and the suffix -ic followed by the word acid.
Examples:
- HCl (hydrochloric acid)
- H₂S (hydrosulfuric acid)
Oxyacids (acids containing hydrogen, oxygen, and one other nonmetal) are named based on the polyatomic ion.
- If the polyatomic ion ends in -ate, the acid ends in -ic acid (e.g., sulfuric acid from sulfate).
- If the polyatomic ion ends in -ite, the acid ends in -ous acid (e.g., sulfurous acid from sulfite).
- Examples:
  - HNO₃ (nitric acid)
  - HNO₂ (nitrous acid)
  - H₂SO₄ (sulfuric acid)
  - H₂SO₃ (sulfurous acid)

Description

This quiz covers the principles of naming ionic and covalent compounds in chemistry. Learn how to identify cations and anions, and apply the correct nomenclature rules for both types of compounds. Test your understanding with examples like NaCl and CO2.