C2

• Ions are charged particles - they can be single atoms or groups of atoms
• When atoms lose or gain electrons to form ions, all they're trying to do is get a full outer shell
• The number of electrons lost or gained is the same as the charge on the ion.
• Oppositely charged ions are strongly attracted to one another by electrostatic forces. This attraction is called an ionic bond.
• Elements in the same groups will form ions with the same charge.
• The elements that most readily form ions are those in:

  • Group 1
  • Group 2
  • Group 6
  • Group 7
• Ionic compounds have a structure called a giant ionic lattice.

  The ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice.
• Ionic compounds all have similar properties:

  • They all have high melting and boiling points
  • When they're solid, they are held in place and can't conduct electricity.
  • When ionic compounds melt, the ions are free to move and they'll carry electric charge.
  • Some ionic compounds dissolve easily in water.
• When non-metal atoms bond together, the share pairs of electrons to make covalent bonds.
• Substances containing covalent bonds usually have simple molecular structures.
• Polymers are long chains of repeating units.
• Giant covalent structures are macromolecules

  1. In giant covalent structures, all the atoms are bonded to each other by strong covalent bonds
  2. They have very high melting and boiling points
  3. They don't contain charged particles
• Allotropes are different structural forms of the same element in the same physical state.
• Metallic bonding involved delocalised electrons.
• Alloys are harder than pure metals.
• The elections in the outer shell of the metal atoms are delocalised. There are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons.
• How strong the forces are depends on:

  • The material
  • The temperature
  • The pressure
• (s) = solid

  (l) = liquid

  (g) = gas

  (aq) = aqueous
• Nanoparticles have a large surface area to volume ratio
• surface area to volume ratio = surface area/volume