Structures and Properties

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Periodic Table

  • Elements in Group 8 are also called noble gases, because they are mainly unreactive
  • The further down each column you go, the less reactive the element
  • Metals are on the left, non metals on the right

Atomic mass:

  • The number of protons and neutrons in the nucleus
  • Always the bigger number

Atomic (proton ) number:

  • Number of protons
  • Also the number of electrons (before bonding)
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Ionic Bonding

  • Bonding between 1 metal and 1 non- metal
  • Where one atom gives electrons to the other atom
  • This gives them both full outer shells, so they become less reactive
  • Eg. Sodium + Chloride = Sodium chloride
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Covalent Bonding

  • Between 2 non- metals
  • Can be written as 'H-H' or 'O=O' (double bond)
  • Electrons are shared between atoms to give both atoms full outer shells
  • Eg. Hydrogen + Oxygen = Hydrogen Oxide (water)
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Metallic Bonding


  • Have some metal and some non- metal properties
  • Semi metals sit on the line between metals and non- metals (Periodic table)


  • Metals form giant structures
  • Delocalised electrons in the outer shells are free to move between ions
  • The bond is describing the bond between the free electrons and the ions
  • These bonds are strong so that the metal can maintain it's shape and have a high melting/ boiling point


  • Lustrous, Hard
  • High density (Heavy for their size)
  • High tensile strength (Resist being stretched)
  • High melting/ boiling points
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Bonds between Atoms and Molecules

Intramolecular Forces:

  • Atoms are held together by strong covalent bonds

Intermolecular Forces:

  • Forces between the molecules are weak
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SMAs & Polymers

Shape Memory Alloys:

  • 2 solid phases
  • The alloy can change between the phases depending on an electrical current or temperature
  • Used in braces, glasses, robots etc.


  • Polymer- large molecule made of an identical repeating unit
  • Monomer- The repeating unit that the polymer is made of
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  • Low density poly (ethene)
  • Flexible, soft
  • Used for bags, cling film etc.
  • Molecules are highley branched- loosely packed
  • Formed from ethene using high pressures & a trace of oxygen


  • High density poly (ethene)
  • Stiff, harder
  • Used for buckets, bottles etc
  • Formed from ethene in a catalyst at 50 degrees C with raised pressures
  • Packed closer together
  • Higher softening temperature & stronger than LDPEs
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Thermosoftening & Thermosetting Plastics


  • Plastic softens when heated & hardens when cooled
  • The polymer molecules can slide over each other
  • They can be easily stretched or moulded into a shape
  • They retain their new shape after heating


  • Covalent bonds are formed between chains of the polymers when heated
  • These give the material a high melting point & increased strength and rigidity
  • They also prevent the plastics from being softened with heat
  • Stronger & not as flammable
  • Don't melt when heated
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  • Measured in nanometres (nm), a billionth of a metre
  • Nanoparticles between 1 and 100 nm
  • Can occur naturally (volcanic ash) or by accident ( combustion)
  • Used in car bumpers to make the parts stronger
  • Used in aluminium to make it more wear resistant
  • Can cut greenhouse gases to prevent climate change
  • Can improve energy storage and efficiency and purify polluted air
  • May be health risks that havent been found yet
  • Atomic weapons could be more accessible
  • Expensive and difficult to develop
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