key concepts

• Structure of an atom

  small central nucleus made from protons and neutrons

  electron shells surround the nucleus
• masses of sub atomic particles

  proton 1

  electron 1

  neutron 1/1836
• charges of subatomic particles

  proton +1

  electron -1

  neutron 0
• atomic number (bottom number) is number of protons
• mass number (top number) is the number of protons + neutrons
• isotope has same number of protons and different number of neutrons
• elements are ordered in increasing atomic mass
• elements in same group have the same amount of electrons in the outer shell
• elements in the same period have the same amount of shells
• metals are on the left hand side of the periodic table
• atoms are most stable when they have a full outer shell
• an ionic bond is between a metal and non metal and involves the transfer of electrons
• ionic compound

  • lattice structure
  • ions held together by strong electrostatic forces of attraction
• a covalent bond is between two non metals that have shared pairs of electrons
• ionic compounds properties

  • high melting point - strong electrostatic forces between ions so require lots of energy
  • conduct electricity when molten or aqueous - ions are charged and free to move
• simple molecular compounds properties

  • low melting and boiling point - weak intermolecular forces that need very little energy to break
  • don't conduct - no charged particles
• giant covalent structure properties

  • high melting point - strong covalent bonds that require alot of energy to break
• polymer is a long chained formed from many monomers
• properties of metals

  • high melting point
  • high density
  • good conductors of electricity
  • malleable
  • shiny
• properties of non metals

  • low boiling point
  • brittle when solid
  • poor conductors of electricity
• mass = moles x Mr
• concentration = mass / volume
• avogadros constant = 6.02 x 10^23
• number of particles = avagadros constant x moles
• density = mass / volume
• strong acid - fully ionises
• weak acid - partially ionises
• general equations

  • acid + metal - salt + hydrogen
  • acid + metal oxide - salt + water
  • acid + metal hydroxide - salt + water
  • acid + metal carbonate - salt + water + carbon dioxide
• allotropes of carbon - diamond

  • each carbon has 4 bonds
  • giant covalent lattice structure
  • cannot conduct - no charged particles
  • hard
  • high melting / boiling point
• allotrope of carbon - graphite

  • each carbon atom has 3 bonds
  • giant covalent lattice structure
  • strong inter molecular forces
  • delocalised electrons flow through structure
• allotropes of carbon - graphene

  • high melting / boiling point
  • strong
  • very light
  • conducts electricity
  • used for electronics