C2

• Ionic bonding


  Atoms gain or lose electrons
• Ionic bonding


  • Strong electrostatic forces attract
• Ionic compounds


  Loads of ionic bonds
• Ionic compounds


  • Attraction in all directions
  • Strong electrostatic force
• Properties of ionic compounds

  • High melting/boiling point
  • Conduct electricity if ions are free to move in a solution or if it is melted and the electrons are free to move
• Ionic compounds require a lot of energy to break the bonds, high temperature is needed
• Ionic bonding involves the transfer of electrons from one atom to another
• Polymers


  Long chains made of monomers
• Covalent bonds


  Strong bonds between atoms
• Types of covalent structures

  • Simple molecules
  • Giant covalent structures
• Covalent bonds


  • Require a lot of energy to break
  • The more molecules, the stronger the attraction
• Non-metals with covalent bonds don't conduct electricity at room temperature (except graphite and fullerenes)
• Giant covalent structures


  • Huge numbers of non-metal atoms
  • Regular repeating lattice
  • Don't conduct electricity even when molten (except graphite and fullerenes)
  • Made from carbon atoms
• Carbon atoms


  Can form up to 4 covalent bonds to make chains and networks
• Graphite/graphene


  • Black and opaque
  • Each carbon forms 3 covalent bonds
  • Sheets of carbon atoms stacked on top of each other with weak bonds between layers
  • Ideal lubricating material
  • High melting point
  • Conduct electricity due to free delocalised electrons
• Fullerenes


  • Large molecules shaped like hollow balls or tubes
  • Different fullerenes contain different numbers of carbon atoms arranged in rings
  • Delocalised electrons allow conduction of electricity
  • Big molecules, high melting point
• simple covalent molecules

  • Strong covalent bonds

  • weak intermolecular forces
  • low melting and boiling point
  • gases and liquid at room temperature
  • lots of energy needed to break covalent bonds
  • more molecules the stronger the attraction
  • don’t conduct electricity due to no free electrons
• Properties of diamond

  • Lustrous and colourless
  • each carbon has four covalent bonds
  • very rigid which makes them really hard
  • Strong cavalent bonds so lots of energy needed to break bonds
  • high melting point
  • doesn’t conduct electricity
  • a good cutting tool
• Metallic bonding


  Metal binding to other metal
• Structure of metals


  • Giant structure of atoms
  • Arranged in a regular pattern
  • Each atom surrounded by electrons in outer shell
  • Outer electrons are shared with all the other atoms
  • Loss of electrons make atoms positive ions
• Metallic properties


  • Strong electrostatic attraction
  • High melting and boiling point
  • Conduct electricity due to delocalized electrons
  • Carry thermal energy
  • Malleable, can be bent or hammered into thin sheets
  • Regular structure allows layers to slide over each other
• Alloy


  • Two or more different elements
  • Different sized atoms to disrupt regular structure so layers can no longer slide over each other
  • Much harder than pure metal
• Allotropes


  Different structural forms of the same element in the same physical state
• Graphene


  • Completely natural, get from ground in form of graphite
• Fullerenes


  • Tubes and sphere formation of sheets of graphene
  • Deliver drugs to areas around the body
  • Industrial catalysts due to large surface area: volume
• Mixture


  Two or more substances that are not chemically combined together and can easily be separated
• Compound


  Two or more different atoms/elements held together by chemical bonds and always found in the same proportion
• Molecule


  Two or more atoms held together by chemical bonds
• Nanoparticles


  • Really small, diameter of 1nm-100nm, can't see them with light microscope
• Nanoparticles


  • Large surface area to volume ratio
• Filtration


  Separate insoluble solid from liquid

  > use of filter paper in filter funnel
• Evaporation


  Separate skiable from solution (liquid)

  > Evaporation dish on tripod that's heated by bunsen burner

  > Cause solvent to evaporate

  > Increase concentration of remaining solution

  > Crystals start to form due to high concentration

  > All solvent eventually disappear leaving dried up crystals

  • Quick and easy process
• Crystallisation


  For objects susceptible to thermal decomposition

  • Use of water bath to heat more gently
  • Some solvent evaporate, crystals start to form
  • Stop heating and allow to cool
  • Solution cools, more solids form as solids are less soluble at cooler temperatures
  • Filter our crystals and dry
• Fractional distillation


  Separate mixture of liquids by differences in boiling points

  • separate mixtures in boiling flask
  • pass through fractionating column, which little glass rods that provide a high surface area, that is cooler at the top than bottom
  • Lower boiling point will evaporate first
  • Passes through condenser
  • Fractionating column ensures one liquid is separated at a time as it condenses liquid back into the flask
• Paper chromatography


  Separate different substances in a mixture to identify them

  1. Draw base line at the bottom
  2. Add sample of ink
  3. Put a small amount of solvent (water or ethanol) in a beaker
  4. Place filter paper in solvent (don't submerge ink or base line)
  5. Place lid on top to prevent solvent from evaporating
  6. Wait for solvent to seep up the paper
  7. The dyes will dissolve in the solvent, each dye will travel at a different rates and separate out to reveal different substance
  8. Insoluble will stay at base line
  9. leaver filter paper to dry
• Nanotubes 


  > used in nanotechnology

  > conducts electricity due to each carbon having one delocalised electron

  > strengthen material due to very high length to diameter ratio without adding weight
• Buckminster fullerene


  > hollow sphere

  > 60 carbon
• Uses of nanoparticles


  > Catalysts- need much less nanoparticle materials

  > Nanomedicine: Fullerenes to deliver drugs around the body directly into cells

  > electrical circuits: due to conducting electricity

  > Solver nanoparticles: Antibacterial properties, infuse onto surgical masks and dressings to reduce risk of infection
• Issues of nanoparticles


  > Relatively new, effects on our body aren't fully understood

  > no evidence that nanoparticles cause harm, bur still need to be tested to be sure

  > Potential effects of suncream that contain nanoparticles: May enter our cells and cause damage to DNA
• Thermal decomposition

  • Some liquids decompose when heated leading to break down of the soluble object