Overview

Atoms bond to achieve a stable electron configuration (usually a full outer shell, like noble gases). The type of bond determines the properties of the substance (e.g., why salt is brittle and metal is bendable).

Core Idea

Octet Rule: Atoms tend to gain, lose, or share electrons to have 8 electrons in their outer shell.

Formal Definition (if applicable)

Ionic Bond: Electrostatic attraction between ions of opposite charge (transfer of electrons). Covalent Bond: Sharing of electron pairs between atoms. Metallic Bond: Attraction between metal ions and delocalized electrons.

Intuition

  • Ionic: One atom gives an electron to another (like giving a gift). They stick together because they are now oppositely charged magnets.
  • Covalent: Two atoms share electrons (like holding hands).
  • Metallic: A sea of electrons flows around positive cores (like a communal pool).

Examples

  • Salt (NaCl): Ionic bond.
  • Water ($H_2O$): Covalent bond.
  • Copper Wire: Metallic bond.

Common Misconceptions

  • “Bonds are physical sticks.” (They are forces of attraction.)
  • “Ionic bonds are weaker than covalent.” (Ionic bonds are very strong in a lattice, but dissolve easily in water.)
  • Electronegativity: A measure of how strongly an atom attracts electrons.
  • Polarity: Uneven sharing of electrons in a covalent bond.
  • VSEPR Theory: Predicting the 3D shape of molecules.

Applications

  • Materials Science: Designing new materials with specific properties.
  • Drug Design: Understanding how drugs bind to receptors.
  • Nanotechnology: Manipulating bonds at the atomic scale.

Criticism / Limitations

The Octet Rule has many exceptions (e.g., Boron, Sulfur). Simple bonding models don’t explain everything (like resonance or molecular orbitals).

Further Reading

  • Pauling, The Nature of the Chemical Bond
  • Lewis, The Atom and the Molecule