Unit 2: Chemistry GCSE AQA

Ionic bonding
1. Particles are oppositely charged ions, which are held by electrostatic attraction
  1. A giant lattice of ions
2. Ionic bonding is the transferring of electrons in the highest occupied energy levels/shells
  1. Occurs in metal and non metal compounds
3. Metal atoms lose elctrons to become positively charged ions
4. Non-metals gain electrons to become negatively charged ions
Covalent bonding
1. When atoms share pairs of electrons they form covalent bonds
  1. Occurs in non-metal compounds
2. Polymers are large molecules of covalent bonds
3. Simple molecules
  1. Strong covalent bonds
  2. Weak intermolecular forces
  3. Low melting points
  4. Low boiling points
  5. Liquid/gas at room temperature
  6. Can't conduct electricity
  7. No free moving electrons
  8. No overall electric charge
4. Macromolecules/giant covalent
  1. Strong covalent bonds
  2. High melting points
  3. High boiling points
  4. Cannot conduct electricity except graphite
  5. Graphite has delocalised electrons - atoms form 3 bonds
    1. Their layers are slippery, making graphite a useful lubricant
      1. Made out of carbon
Metallic bonding
1. A lattice of metal atoms with delocalised electrons
2. Metals are good conductors of electricity
  1. This is because their delocalised electrons carry charge
  2. Strong metallic bonds
  3. Also thermal energy conductors; electrons transfer energy
3. Alloys
  1. A mixture of two or more elements, with at least one metal element
  2. Various atom sizes
    1. This distorts the layers meaning a greater force is needed to slide these layers over each other
  3. Harder and stronger than a pure metal
Diagram pros & cons
1. 3D diagrams
  1. Shows how the ions are arranged
  2. Doesn't give details on how the ions were formed
2. 2D diagrams
  1. Gives a limited view of how the ions are arranged in a crystal
  2. Lacks detail on how the ions were formed in making the ionic bond
3. Dot & Cross diagrams
  1. Provides the electronic structure of the ions in a crystal lattice of the ionic compound
  2. Cannot show how the ions are arranged
Propertes of matter
1. Solids
  1. Particles are in a tight, fixed, regular pattern
  2. Low energy
  3. Vibrate
2. Liquids
  1. Flow, take the shape of their container
  2. Randomly arranged
  3. Greater energy than a solid
  4. Particles move around each other
3. Gases
  1. Far apart
  2. Particles move quickly in all directions
  3. Can be compressed
  4. High energy
Graphenes, Fullerenes & Nanotubes
1. Graphenes are single layers of graphite
  1. Strong covalent bonds
    1. High melting point
    2. Delocalised electrons
2. Fullerenes are molecules of carbon with hollow shapes
  1. Buckminsterfullerene
    1. 60 carbon atoms
    2. Low melting point
    3. Strong covalent bonds
    4. Weak intermolecular forces
  2. Nanotubes
    1. High tensile strength
Nanoparticles
1. 1nm to 100nm in size
  1. Could be dangerous inside the body
    1. Could bind to toxic substances
2. Large surface area : volume ratio
  1. Nanoparticulate substances can act as catalysts
3. Medical treatments, sunscreen, cosmetics
  1. Invisible on skin
    1. Often clump together, difficult to apply

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Unit 2: Chemistry GCSE AQA

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