Bonding / structure

• Giant covalent: Diamond, graphite, graphene, silicondioxide (sand)
• Molecule: something that is covalently bonded
• • Covalent - non metal + non metal
• Ionic - metal + non-metal
• Metallic - metal + metal
• Why are metals ductile: Metal atoms (or ions) are in layers that can slide over each other.
• Why are metals strong: Positive ions are surrounded by a sea of delocalised electrons which need alot of energy to break
• Why do metals conduct electricity: Electrons in metals are free to move around and carry the charge
• Why do metals conduct heat: Eletrons in metals are free to move around and carry the thermal charge
• Ionic bonding occurs between oppositely charged ions
• Isotope: An element with the same amount of protons and a different amount of neutrons
• Ion: Charged particle

  Anion: Negatively charged ion

  Cation: Positively charged ion
• Ionic bond: Strong electrostatic forces of attraction between opppositly charged ions
• Properties of simple molecular substances:

  • Low melting points and boiling points.
  • Weak intermolecular forces between molecules.
  • Strong covalent bonds between each atoms of each molecule.
  • Cannot conduct electricity.
• Why do simple molecules have low melting and boiling points: Weak intermolecular forces of attractions that can break easily
• Why can't simple molecules conduct electricty: Electrons aren't free to move around or no charged particles to carry the charge
• Ionic compounds:

  • High strength bonds
  • High melting and boiling points
  • Conduct electricity when liquid
• Why do metals have high melting and boiling points:

  Strong metallic bonds which require alot of energy to break.
• A= Graphite

  B= Diamond

  C= Fullerene

  D= Nanotube

  E= Graphene

  
• Why is 9 carat gold is used instead of pure gold:

  • 9 carat gold is cheaper
  • Pure gold is soft
  • Can change the colour.
• Why do farmers use ammonium nitrate on thier fields:

  Good fertilisers
• Why is the ball and stick model inaccurate:

  Model doesn't show that the forces of attarction between ions usually act in all directions.
• Why can ionic compounds conduct electricity when molten:

  Ions are free to move around and carry the charge.
• How is electricity conducted in metals:

  Positive ions are in layers with delocalised electrons which can move through the metal and carry the charge.
• Why are alloys stronger than pure metals:

  • In alloys, atoms are in different sizes so greater force is required for the layers to slide over each other.
  • Layers in alloys are distorted.
• Why aren't coins made out of pure copper:

  Pure copper is too soft.
• Simple covalent:

  • Low melting and boiling points.
  • Liquid or gas at room temp.
  • Can't conduct electricity.
• Giant covalent:

  • High melting and boiling points.
  • Solids at room temp.
  • Can't conduct electricity (only graphite can).
• How graphite is used as lubricant for high heat machines:

  1. Graphite has a giant covalent structure so it has a high melting and boiling point so it can withstand high heat.
  2. Graphite is made up in layers that can easily slide over each other which is ideal for lubicants.
• Allotrope:

  Different forms of the same element in the same state.
• Advantages and disadvantages of using nanoparticles in sun creams:

  +, Better coverage.

  +, More protection from the sun's ultraviolet rays.

  -, Potential cell damage to body.

  -, Harmfull effects on the enovironment.
• Why can graphite conduct electricity?

  Each carbon atom has 1 delocalised electron which can move move freely and carry the charge.
• What fullerenes can be used for:

  • Catalyst in chemical reactions.
  • Delivery of medicines around the body.
• Fullerenes are useful as catalysts because they have a high surface area to volume ratio.