chem paper 1

• plum pudding model: discovery of electron
• alpha particle scattering experiment: mass of an atom was at the nucleus(had a charge)
• neil bohr: electron shells
• james chadwick: existence of neutrons
• concentration(g/dm3) = mass of solute/volume of solvent
• mendeleev: ordered table by atomic mass
• newland: ordered table by atomic weight
• metals: elements that react to form positive ions
• non-metals: elements that dont form positive ions
• displacement reaction: a more reactive metal will displace a less reactive metal from its compound
• exothermic reaction: transfers energy to the surroundings
• reduction: gain electrons
• endothermic reaction: takes in energy from the surroundings
• oxidation: loss of electrons
• covalent bonding : - non metals sharing pairs of electrons

  - compounds of non-metals

  - non-metal elements
• ionic bonding: - metal + non-metal

  - transfer of electrons

  - dot and cross diagram to represent
• ionic compounds:

  regular lattice structure

  strong electrostatic forces of attraction

  attraction between oppositely charged ions

  cannot conduct when solid

  high melting + boiling points
• simple molecular substances:

  made up of molecules containing a few atoms joined

  e.g. H2, N2, Cl2, H2O, HCl, CH4, O2

  forces of attraction are weak
• 1066- William the conqueror becomes king of england