C2-Bonding, Structure and the Properties of Matter

• Ions are charged particles
• Group 1 and 2 elements are metals and they lose electrons to form positive ions
• Group 6 and 7 are non-metals and they gain electrons to form negative ions
• The three chemical bonds :

  • Ionic
  • Covalent
  • Metallic
• Ionic Bonding :

  • particles that are oppositely charged
  • occurs in compounds formed from metals combined with non-metals
• Substances held by ionic bonds :

  • high melting/ boiling points as large amounts of energy are required to break the bonds
  • don't conduct electricity as ions are held in fixed position and cant move unless it is in molten or dissolved
• Covalent bonding :

  • particles are atoms which share pairs of electrons
  • occurs in compounds of non-metals
• Simple molecular structures have strong covalent bonds in between atoms and weak intermolecular forces between the molecules
• Substances bonded by covalent bonds have low melting/boiling points as little energy needed to overcome weak intermolecular forces
• Polymers are long chains of molecules made from joining lots of small molecules (monomers) which are held by covalent bonds
• Polymers are solid at room temperature as the intermolecular forces are strong
• Diamond:

  • each carbon atom is covalently bonded to 4 other carbon atoms
  • high melting point as the strong covalent bonds between atoms require large amounts of energy to break
  • hard because each carbon atom is covalently bonded to 4 other carbon atoms
  • don't conduct electricity as it doesn't have any free electrons
• Graphite :

  • each carbon atom is covalently bonded to 3 other carbon atoms
  • high melting point as the strong covalent bonds require large amounts of energy to break
  • soft and slippery as the layers are held by weak intermolecular forces, meaning layers can slide over easily
  • can conduct electricity as it has delocalised electrons and can carry a charge through the structure
• Graphene :

  • singular layer of graphite
  • delocalised electrons that can carry a charge through the structure
  • can make materials strong without adding weight
• Fullerenes are molecules of carbon atoms with a hollow shape
• Uses of fullerenes :

  • delivery of drugs to specific parts of the body
  • used in lubricants to reduce friction in machinery
  • used in nano-technology
• Metallic bonding occurs in metallic elements
• Metals have high melting and boiling points due to the strong electrostatic forces of attraction between the positive metal ions and the sea of delocalised electrons are strong and require large amounts of energy to break
• Metals are good electrical conductors as they sea of delocalised electrons carry a charge through the structure
• Metals are good thermal conductors as delocalised electrons can carry thermal (heat) energy though the structure
• Metals are malleable (can be bent and shaped easily) as metals consist of layers of atoms which can slide over one another
• Alloys are a mixture of two or more metals or a metal with another element
• Alloys are harder than normal metals as different elements have different sized atoms. When another element is added to a pure metal the layers will distort, making it harder to slide over each other
• Coarse particles have a size of 1-10µm
• Fine particles have a size of 100nm
• Nano particles have a size of 1-100 nm
• Uses of nano-particles :

  • in medicine to deliver drugs into the right cells in the body
  • in electronics in tiny circuit boards
  • in cosmetics as they improve moisturisers by not making them oily
  • in deodorants as silver nanoparticles have antibacterial properties
  • as catalysts due to large SA:V ratio
• Effects of nano-particles:

  • cell damage
  • environmental damage