chemistry paper 1

• Order of atom discovery

  • Electron
  • Nucleus
  • Proton
  • Neutron
• Electron

  Found first because it has a charge and comes away from atoms
• Neutron

  Found last because it has no charge
• Order of people discovery

  • Thomas
  • Rutherford
  • Bohr
  • Proton
  • Chadwick
• Thomas

  Found electron
• Rutherford

  Found nucleus
• Bohr

  Found energy levels
• Chadwick

  Found neutron
• Acronym for order ion discovery is TEn Red Nucleus' Brought Electrons a Proton with Canned Neutrons
• The periodic table used to be organised by atomic weight
• Mendeleev


  Left gaps in his periodic table because he predicted new elements
• Mendeleev was right to not place elements in a strip order of atomic weight because of isotopes with have a different mass but the same chemical properties
• Atomic weight

  Relative atomic mass
• Ions

  Can be single atoms or a group of atoms
• Ions


  Are charged atoms
• Metal ions


  Lose electrons to form positive ions
• Non-metal ions


  Gain electrons to form negative ions
• Ionic bonding


  The transfer of electrons
• Ionic bonding


  Between a metal and a non-metal
• Drawing ionic bonds

  Draw them separately in brackets with the charge on the top right
• Ionic bonding

  The metal loses an electron and non-metal gains one
• Ionic bonds

  The two ions stay together due to electrostatic forces
• Ionic compounds

  • Have a regular lattice structure (a giant ionic lattice)
  • Have strong electrostatic forces in all directions
  • Have high melting points, cannot conduct when a solid, can conduct when melted or dissolved in water
• Covalent bonding

  Between two non-metals
• Covalent bonds

  Share pairs of electrons
• Drawing covalent bonds

  Use dot cross or displayed formulas
• Covalent bonding

  The positively charged nuclei are attracted to the shared pair of electrons by electrostatic forces
• Covalent bonding

  Can be between compounds and elements
• Simple molecular substances

  • Made of a few atoms covalently bonded
  • Bonds between atoms are strong but forces between these molecules are weak
  • Have low melting point, often gas or liquid at room temperature and don't conduct electricity as there is no free electrons or ions
• Polymers

  Long chains of repeating units
• Atoms in a polymer

  Joined together by covalent bonds
• Polymers

  • Have a higher boiling point than simple molecular substances
• Drawing polymers molecular formula

  In brackets of shortest repeating units with bonds going outside brackets and n on the bottom right
• The 'n' in a polymers molecular formula

  Means a large number
• Giant covalent structures

  • Have very high melting point and don't conduct electricity (apart from graphite)
• Diamond

  Every carbon atom has 4 bonds in a very rigid structure
• Graphite

  • Each carbon atom has 3 bonds
  • Has layers of hexagons weakly held together
  • Each carbon atom has a delocalised electron
• Silicone dioxide is made of silicon and oxygen
• Sand is made of silica
• Allotropes


  Different structural forms of the same element