Differences Between Ionic and Covalent Bonds

  1. Nature of Bond:
    • Ionic Bond: Formed when electrons are transferred from one atom to another, resulting in the formation of oppositely charged ions (cation and anion) that attract each other. Typically occurs between a metal and a non-metal.
    • Covalent Bond: Formed when two atoms share electrons to achieve a stable electron configuration. Typically occurs between two non-metals.
  2. Electron Movement:
    • Ionic Bond: Involves complete transfer of electrons.
    • Covalent Bond: Involves sharing of electrons.
  3. Structure:
    • Ionic Bond: Results in a crystal lattice structure, which is a repeating 3D arrangement of ions.
    • Covalent Bond: Leads to the formation of discrete molecules or, in some cases, network structures (e.g., diamond, quartz).
  4. Strength:
    • Ionic Bond: Strong electrostatic attraction between ions in the lattice.
    • Covalent Bond: Strength varies, but generally depends on the number of shared electrons and the distance between the nuclei.

Properties of Substances Formed:

  1. Melting and Boiling Points:
    • Ionic Compounds: Typically have high melting and boiling points due to strong electrostatic forces in the lattice.
    • Covalent Compounds: Generally have lower melting and boiling points because of weaker intermolecular forces (except in network covalent structures).
  2. Electrical Conductivity:
    • Ionic Compounds: Conduct electricity when melted or dissolved in water because ions are free to move.
    • Covalent Compounds: Poor conductors of electricity in most cases because they lack free-moving charged particles.
  3. Solubility:
    • Ionic Compounds: Often soluble in polar solvents (e.g., water) due to the interaction between ions and the solvent.
    • Covalent Compounds: Solubility depends on polarity; polar covalent compounds dissolve in polar solvents, while nonpolar covalent compounds dissolve in nonpolar solvents.
  4. Hardness and Brittleness:
    • Ionic Compounds: Typically hard but brittle due to the rigid lattice structure; when stressed, like-charged ions may come into proximity and repel, causing the crystal to shatter.
    • Covalent Compounds: May be soft (e.g., waxes) or hard (e.g., diamond), depending on the molecular or network structure.
  5. Appearance:
    • Ionic Compounds: Often form crystalline solids with a characteristic geometric shape.
    • Covalent Compounds: Can exist as solids, liquids, or gases, with a variety of appearances.

Summary:

  • Ionic bonds create substances with high melting points, good electrical conductivity in molten/dissolved states, and characteristic crystalline shapes.
  • Covalent bonds produce substances with diverse physical states, lower melting/boiling points (except network covalent solids), and generally poor electrical conductivity.