Ionic Compounds and Ion Formation

Ion Formation

• Atoms and Electrons: Atoms of certain elements gain or lose electrons to achieve noble gas electron configuration.
• Ions: In the process, they become ions:
  • Cations: Positively charged ions (lose electrons).
  • Anions: Negatively charged ions (gain electrons).

Ionic Compounds

• Definition: Compounds consisting of two or more ions bound by electrostatic interactions between positive (cation) and negative (anion) charges.
• Types of Ions:
  • Monoatomic: Consist of a single atom with a charge.
  • Polyatomic: Consist of multiple atoms but have a single formal charge.

Formation Process

• Ratio Formation: Cations and anions combine in specific ratios to form neutral compounds.
• Common Elements: Metal and Non-Metal: Typically involves a metal cation and a non-metal anion.

Predicting Ionic Compounds

• Charges and Ratios: Understanding common ion charges helps predict how ions will combine.

Examples of Ionic Compounds

1. Sodium and Chlorine:

   • Sodium (Na) transfers its valence electron to Chlorine (Cl).
   • Ions Formed: Na⁺ and Cl⁻
   • Compound: NaCl (1:1 ratio)

2. Sodium and Oxygen:

   • Oxygen tends to form O²⁻ ions.
   • Ions Needed: Two Na⁺ ions needed to combine with one O²⁻ to form Na₂O.

3. Aluminum and Oxygen:

   • Aluminum forms Al³⁺ ions.
   • Ions Needed: Two Al³⁺ ions and three O²⁻ ions to achieve a neutral compound, resulting in Al₂O₃.

4. Potassium and Sulfate Ion (SO₄²⁻):

   • Ions Needed: Two K⁺ ions combine with one SO₄²⁻ to form K₂SO₄.

Molecular Formula of Ionic Compounds

• Neutrality: Molecular formulas do not list charges, as the compound as a whole is neutral.
• Understanding Composition: Recognizing compositions helps understand the molecular structure of ionic compounds.