How do molecules differ from ionic compounds

Molecules and ionic compounds differ mainly in how their atoms bond.

• Molecules are formed when non-metal atoms share electrons through covalent bonds.
• Ionic compounds are formed when a metal atom transfers electrons to a non-metal, creating oppositely charged ions that stick together through electrostatic attraction.

This key difference affects their structure, composition, and physical properties.

Bonding

• Molecules (Covalent Compounds): Atoms share electrons, forming strong covalent bonds inside each molecule.
• Ionic Compounds: A metal loses electrons and a non-metal gains them, producing positive (cation) and negative (anion) ions that attract each other.

Structure

• Molecules: Exist as separate, neutral units (individual molecules).
• Ionic Compounds: Form a 3D lattice of ions held together by strong electrostatic forces, not as separate molecules.

Composition

• Molecules: Usually made from two or more non-metals.
• Ionic Compounds: Made from a metal + non-metal reaction.

Physical Properties

• Molecules:
  • Lower melting and boiling points.
  • Forces between molecules (intermolecular forces) are weaker than ionic bonds.
• Ionic Compounds:
  • High melting and boiling points.
  • Hard but brittle solids.
  • Conduct electricity only when melted or dissolved in water, because ions must be free to move.