Ionic Bonding

Ionic Bonding

Ionic bonding usually occurs when a non-metal atom reacts with a metal atom. The non-metal gains an electron to fill its outer shell, while the metal atom loses one, creating balanced positive and negative charges.

Basic Concepts

  • Ionic compounds are formed by ions and are held together by the attraction between oppositely charged ions.
  • They have no overall charge as the total positive charge of the cation is balanced by the total negative charge of the anion.
  • Metals often form cations (positively charged ions) and non-metals form anions (negatively charged ions).
  • The number of electrons lost or gained is determined by the valence electron structure of atom.
  • The naming of ionic compounds always introduces the cation first, followed by the anion.

Properties of Ionic Compounds

  • Ionic compounds exist as crystals and are often hard because of the strong lattice structure.
  • They have high melting and boiling points due to the strong ionic bonds.
  • They typically dissolve in water and other polar solvents.
  • In a molten or dissolved state, ionic compounds are able to conduct electricity because the ions are free to move.
  • They’re usually brittle; when force is applied, the ionic bonds may shift, causing the repulsion between ions of similar charge.

Structure of Ionic Compounds

  • In an ionic crystal like sodium chloride (NaCl), each ion is surrounded by ions of the opposite charge arranged in a giant ionic lattice.
  • This type of arrangement maximises attractive forces and minimises repulsive forces. This structure contributes to their high melting and boiling points.

Energy Changes in Ionic Bonding

  • In ionic bonding, energy is released when the ions come together to form a compound, which makes the ionic bonding process an exothermic reaction.
  • By studying the changes in energy, a more detailed understanding is developed about why ionic compounds form and how stable they are.

Remember, ionic bonding involves a transfer of electrons from one atom to another. The resulting compound has properties very different from the constituent elements.