Metallic Bonding -Chemistry

• Properties of metals


  • They conduct heat: let's heat flow through them easily
  • They conduct electricity: let's electricity flow through them easily
  • They have high melting points
  • They are strong and tough but bendable
  • They will shine when freshly cut or scratched
  • They have higher densities than non metals
• Alloy


  A mixture of a metal plus other metals or non metals, eg carbon
• Pure metals are too soft for many uses, so they can be made harder by adding another element to the pure metal forming an alloy
• Metals are good conductors of heat and electricity


  Because they have free delocalised electrons that are free to move throughout the structure
• Metals have high melting points


  Because a lot of energy is needed to overcome the attraction between metal ions and delocalised electrons
• Elements


  All of the atoms are the same
• Compounds


  Contain two or more different elements chemically combined in fixed proportions
• Mixtures


  Different elements or compounds, but they are not chemically combined
• Filtration


  Used to separate a soluble solid from a liquid
• Crystallisation


  1. Used to separate a soluble solid from a liquid

  2. Can happen faster for the water to evaporate by gently heating the solution
• Simple distillation


  Used to separate a soluble solid from a liquid, but you save the water
• Fractional distillation


  Used to separate two or more liquids with different boiling points
• Paper chromatography


  Used to separate dissolved substances from another based on their different solubilities, e.g. ink and food colouring
• Plum pudding model


  • An atom is a ball of positive charge with negative electrons embedded in it
• Alpha scattering experiment


  1. Scientists fired tiny, positive alpha particles at a piece of gold foil

  2. Some particles deflected (changed direction) as they passed through

  3. Some bounced back

  4. This tells us the centre of the atom must have a positive charge as some atoms were deflected
• John Newlands


  • Arranged elements in increasing atomic weight, invented "Law of Octaves"
• Dmitri Mendeleev


  • Arranged elements in increasing atomic weight, switched some elements so they would fit into the same group with similar patterns
  • Left gaps in areas he thought an element was missing, predicted the properties of undiscovered elements with elements in the same group
• Atomic mass number


  • The centre part of the atom is the nucleus
  • Electrons have a negative charge (-1)
  • Protons have a positive charge (+1)
  • Neutrons have a neutral charge (0)
• Isotopes


  Atoms of the same element with a different amount of neutrons, but the same amount of protons
• Ions


  Atoms that have an overall charge, because they have lost or gained electrons