ionic bonding,metallic bonding, and structure

• Ions


  Atoms that have gained or lost electrons, resulting in a charge
• Formation of ions

  1. Atom loses electron

  2. Atom gains electron
• Sodium atom


  • 11 protons, 11 electrons, overall charge 0
  • Sodium ion, 11 protons, 10 electrons, overall charge 1+
• Ionic bonding


  When metal atoms transfer electrons to non-metal atoms
• Ionic structure


  • Positive and negative ions attracted by strong electrostatic force
  • Many billions of ions bonded together in 3D structure
• Determining ionic formula


  1. From bonding diagram

  2. From lattice diagram
• Metal atoms lose electrons to become positive ions, non-metal atoms gain electrons to become negative ions
• Ionic properties


  • High melting points due to strong electrostatic attraction
  • Solid ionic substances do not conduct electricity, but molten/dissolved do conduct
• Metals


  Atoms that make up metals form layers, with the electrons in the outer shells delocalised and free to move through the whole structure
• Metallic structure

  • Positive metal ions are attracted to the 'sea' of delocalised electrons by the electrostatic force of attraction
• Metallic properties


  • Pure metals are malleable (soft) because the layers can slide over each other
  • Metals are good conductors of electricity and thermal energy because delocalised electrons are free to move through the whole structure
  • Metals have high melting and boiling points because the electrostatic force of attraction between metal ions and delocalised electrons is strong, so lots of energy is needed to break it
• Alloys

  • Pure metals are often too soft to use as they are
  • Adding atoms of a different element can make the resulting mixture harder
  • New atoms will be a different size to the pure metal's atoms
  • This will disturb the regular arrangement of the layers, preventing them from sliding over each other
• Alloy

  The harder mixture resulting from adding atoms of a different element to a pure metal
• Alloys

  • pure iron
  • iron alloy
• Metallic properties: Delocalised electrons are able to move through the whole structure
• Metallic properties: Have high melting and boiling points because the electrostatic force of attraction between metal ions and delocalised electrons is strong so lots of energy is needed to break it
• Ion

  Atom that has lost or gained electrons
• Elements that form ionic bonds


  • Metals
  • Non-metals
• The electrostatic force of attraction holds oppositely charged ions together
• Structure of a giant ionic lattice


  • Regular structure of alternating positive and negative ions, held together by the electrostatic force of attraction
• Ionic substances have high melting points because the electrostatic force of attraction between positive and negative ions is strong and requires lots of energy to break
• Ionic substances don't conduct electricity when solid because the ions are fixed in position so cannot move, and there are no delocalised electrons
• Ionic substances can conduct electricity when melted or dissolved because the ions are free to move and carry charge
• Structure of a pure metal


  • Layers of positive metal ions surrounded by delocalised electrons
• Bonding in a pure metal

  Strong electrostatic forces of attraction between metal ions and delocalised electrons
• Properties of pure metals

  • Malleable
  • High melting/boiling points
  • Good conductors of electricity
  • Good conductors of thermal energy
• Metals are malleable because the layers can slide over each other easily
• Metals have high melting and boiling points because the electrostatic force of attraction between positive metal ions and delocalised electrons is strong and requires a lot of energy to break
• Metals are good conductors of electricity and thermal energy because the delocalised electrons are free to move through the metal
• Alloy


  Mixture of a metal with atoms of another element
• Alloys are harder than pure metals because the different sized atoms disturb the layers, preventing them from sliding over each other