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• Ion


  Electrically charged particle, formed when an atom or molecule gains or loses electrons
• Atom


  The smallest part of an element that can exist
• Charge


  Property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative.
• Electron


  Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons
• Metal


  Shiny element that is a good conductor of electricity and heat, and which forms basic oxides
• Non-metal


  Element that is a poor conductor of electricity and heat, and which forms acidic oxides
• Forming positive ions


  1. Metal atoms lose electrons from their outer shell

  2. The ions formed have full outer shells

  3. The ions have the electronic structure of a noble gas (group 0 element), with a full outer shell
• Forming negative ions


  1. The outer shells of non-metal atoms gain electrons

  2. The ions formed are negative, because they have more electrons than protons

  3. The ions have the electronic structure of a noble gas (group 0 element), with a full outer shell
• For elements in groups 1, 2 and 3, the number of electrons lost is the same as the group number
• For elements in groups 6 and 7, the charge on the ion is equal to (8 minus group number)
• Ions


  Formed by the transfer of electrons
• Ion charges and groups

  • Group 1 Element Na Ion charge + Ion symbol Na +
  • Group 2 Element Mg Ion charge 2+ Ion symbol Mg 2+
  • Group 6 Element O Ion charge 2- Ion symbol O 2-
  • Group 7 Element Cl Ion charge - Ion symbol Cl -
• Ionic compound


  A giant lattice structure made up of charged particles called ions, with strong electrostatic forces of attraction
• Ionic lattice


  • Regular, repeating arrangement of ions
  • Oppositely charged ions next to each other
• A single grain of salt may contain 1.2 × 10^18 (1,200,000,000,000,000,000) ions
• The lattice arrangement continues in three dimensions, which is why solid ionic compounds form crystals with regular shapes
• Ionic bonding


  Strong electrostatic forces of attraction between the oppositely charged ions, acting in all directions in the lattice
• Different types of models are used to represent giant ionic structures, each with advantages and limitations
• The two-dimensional space-filling model clearly shows the arrangement of ions in one layer, but does not show how the next layer is arranged
• The three-dimensional ball and stick model shows the arrangement of ions in a larger section of the crystal, but using sticks for bonds is misleading because the forces of attraction actually act in all directions
• The three-dimensional model is also misleading because it shows lots of free space between the ions, which there isn't
• Ionic compound


  Made up of charged particles, called ions. Has a giant lattice structure with strong electrostatic forces of attraction.
• Ionic compounds


  • Have regular structures, called giant ionic lattices
  • Have strong electrostatic forces of attraction acting in all directions between the oppositely charged ions
• Ionic lattice


  The regular arrangement of ions in an ionic substance
• Properties of ionic compounds

  • High melting and boiling points
  • Can conduct electricity when melted or in solution
  • Cannot conduct electricity in the solid state
• Ionic compounds have high melting and boiling points


  Because energy must be transferred to overcome the strong electrostatic forces of attraction between the oppositely charged ions
• Ionic compounds can conduct electricity when melted or in solution


  Because the ions are then free to move from place to place
• Ionic compounds cannot conduct electricity in the solid state

  Because the ions are held in fixed positions and cannot move
• The strength of the ionic bonds depends on the charge on the ions. Ions with higher charge will have stronger forces between them, so will need more energy to overcome these forces.
• Covalent bond


  A shared pair of electrons
• Covalent bonding


  Forms molecules
• Substances with small molecules

  • Have low melting and boiling points
  • Do not conduct electricity
• A covalent bond is a shared pair of electrons
• Covalent bonding forms molecules
• Substances with small molecules have low melting and boiling points, and do not conduct electricity
• Melting point


  The temperature at which a solid changes into a liquid as it is heated
• Boiling point


  The temperature at which a substance rapidly changes from a liquid to a gas
• When a simple molecular substance melts or boils

  It is the intermolecular forces that are broken, not the covalent bonds in each molecule
• Intermolecular forces


  Weak attractive forces between molecules
• Intermolecular forces are much weaker than the strong covalent bonds in molecules