Bonding

• what elements does ionic bonding happen between?

  metal and non metal
• how is the compound lithium chloride formed

  1. the lithium atom gives one electron to chlorine
  2. Li+ ion is formed
  3. the chlorine gains one electron from lithium
  4. Cl- ion is formed
  5. this forms a strong electrostatic attraction
  6. Both elements have full outer shells
  7. Compound LiCl is formed
• Properties of ionic compounds

  high MP and BP due to strong electrostatic attraction which requires a lot of energy to break

  Cant conduct when solid as ions stuck in place

  can conduct when molten and aqueous as ions are free to move
• if an element needs x electrons in a covalent bond it will share x electrons
• covalent bonds happen between non metals
• what are the properties of small covalent molecules

  Low MP and BP as there are weak intermolecular forces between the molecules

  do not conduct electricity as they don't have a charge
• what is metallic bonding

  positive metal ions surrounded by a sea of delocalised electrons
• why are metals malleable, have a high MP and can conduct

  Malleable as the layers can slide over each other

  conduct as delocalized electrons can carry the charge

  High MP as the metallic bonds are strong
• what are alloys


  a mixture of metals with different-sized atoms making it hard to distort layers which increases its usefulness
• limitation of the dot and cross model


  suggests that electrons are different shapes when they are not
• limitation of the ball and stick model

  atoms are held by bonds not sticks
• limitation of the 2d stick diagram


  only shows shared electrons
• limitation of the 3d stick diagram

  doesnt show us the unshared electrons
• limitations of particle theory

  doesnt take into account the shape and size of the particles

  no forces shown between the particles
• properties of diamonds


  solids at room temp due to high MP

  each carbon bonded with 4 other carbons so it's hard

  cant conduct as there are no free electrons
• properties of graphite


  soft and slippery as the layers are held by weak forces

  High MP as each carbon is bonded to three other carbons

  can conduct as the delocalized electrons carry the charge
• graphene properties


  single layer of graphite

  conductor as delocalized electrons can carry the charge

  High MP as the covalent bonds are strong
• buckminster fullerene uses


  60 carbon atoms

  lubricants in machines

  drug delivery

  catalysts
• Nanotubes properties


  long cylinders of fullerenes- form rings with 5 or 6 carbon atoms

  high tensile strength

  good conductors

  used to reinforce materials
• what is a polymer


  formed by the long chain of monomers

  double covalent bond when monomer e.g. ethene

  single covalent bond when polymer e.g. polyethene
• size of coarse particles

  1 * 10^-3 - 2.5 * 10^-6 m
• size of fine particles

  100-2500 nm
• nanoparticles size


  1-100 nm
• why do nanoparticles have an advantage over larger materials

  huge SA: V ratio

  much smaller quantity needed than materials of larger sizes
• what are nanoparticles uses and its disadvantage

  sunscreen, deodorant, catalysts

  however no one knows the long term effects of nanoparticles