Bonding, structure and matter

• Ionic bonds are between …

  metals and non-metals
• What is a giant ionic lattice held together by

  strong electrostatic forces of attraction between oppositely charged ions
• how do represent ionic compounds

  • two dimensional space-filling model
  • three dimensional ball and stick
• two dimensional space filling model

  • shows arrangement of ions on 1 layer
  • ❌doesn’t show next later of ions arranged
• three dimensional ball and stick

  ❌ misleading (forces of attraction between ions in all directions)

  ❌shows lots of free space between ions which there isn’t a
• What melting and boiling points do ionic properties have

  • high melting and boiling point
  • because ionic lattice has a large number of ions
  • lots of energy needed to overcome
• what does the strength of the ionic bonds depend on

  • the charge on the ions
  • ions with higher charge have stronger forces and need more energy to overcome
• When can ionic compounds conduct electricity?

  • melted to form liquid
  • dissolved in water to form aqueous solution
• why can’t ions conduct electricity in solids

  • ions held in fixed positions
  • cannot move
• What is silicon dioxide

  • example of a giant covalent structure
  • which contains many silicon and oxygen atoms
• melting and boiling points of giant covalent molecules

  • solids at room temp
  • very high melting + boiling points
  • large amounts of energy needed to overcome strong covalent bonds
• Can covalent structures conduct electricity

  • no because there’s no charges particles free to move (except graphite)
• Diamond

  • each carbon atom joined to four other carbon atoms by strong covalent bonds
  • form a regular tetrahedral structure
  • no free electrons
• what are covalent bonds between

  • two non metals
• Graphite structure

  • each carbon atom forms 3 covalent bonds with other carbon atoms
  • carbon atoms form hexagonal rings
  • no covalent bonds between layers
  • one delocalised electrons from each atom
• Properties and uses of graphite (electricity)

  • delocalised electrons free to move between layers on graphite, so can conduct electricity
  • makes graphite useful for electrodes in batteries and for electroloysis
• Properties and uses of graphite (layers)

  • forces between layers weak
  • layers can slide over each other
  • useful as a lubricant
• Properties and uses of diamond

  • very hard
  • useful for cutting tools
  • such as oil rigs
• graphene structure

  • single layer of graphene
  • strong covalent bonds
  • very high melting point
  • very strong
• Graphene conductivity

  • conducts electricity
  • because it has delocalised electrons
• What is graphene useful for

  electrons and making composites
• fullerenes structure

  • molecules of carbon atoms with hollow shapes
  • made of hexagonal rings
• examples of fullerene

  • buckminsterfullerene
  • nanotubes
• Buckminsterfullerene structure

  • first fullerene discovered
  • 60 carbon atoms joined by strong covalent bonds
• buckminsterfullerene properties

  • weak intermolecular forces
  • little energy to overcome
  • slippery
  • low melting point
• nanotubes structure

  • layer of graphene rolled into a cylinder
  • length of nanotube very long compared to width
• nanotubes properties

  • high tensile strength
  • strong and conduct electricity
• nanotubes uses

  • used for nanotechnologys
  • electronics
  • specialised materials
• polymers

  • very large molecules
• polymer properties

  • intermolecular forces strong compared to small molecules
  • polymers melt at higher temps than substances with small molecules
• Metallic bonding

  • giant structures of atoms arranged in a regular pattern
  • electrons from outer shells delocalised
  • and free to move through the whole structure
• properties of metals

  • electrical conductors
  • good conductors of thermal energy
• what kind of melting + boiling point do metals have

  • high melting and boiling points
• why do metals have high melting and boiling points

  • metallic bonding in the giant structure of a metal is very strong
  • large amounts of energy needed to overcome the metallic bonds
• Alloys

  • many pure metals too soft for many uses
  • made harder by adding another element to pure metals
• why are pure metals soft

  • atoms arranged in layers
  • so soft and easily bent and shaped
  • because only small force needed for layers to slide over each other
• Why are alloys harder and stronger?

  • atoms add different sizes
  • distorting the layers
  • greater force required for layers to slide over each other
• what is nanoscience

  • the study of structures between 1 and 100 manometers in size
• properties of nano particulates materials

  • different from properties in bulk, powders lumps or sheets
  • tiny size nanoparticles compared to same material in bulk
  • large surface area to volume ratios compared to sane material in bulk
• properties and uses of nanparticles

  • medical treatments
  • cosmetics deodorants and sunscreens
  • electronics
  • catalysts