metals

• Metallic bonds are strong electrostatic forces of attraction between cations and the sea of delocalised electrons
• An alloy is a mixture of a metal with one or a few other elements.
• In pure metals, layers of atoms with same size can slide over each other easily. In alloys, layers of atoms cannot slide over each other easily as atoms of alloying elements with different sizes disrupt the orderly arrangement of the metal atoms.
• The more easily the electrons are lost, the more reactive the metal.
• reactivity series: potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, lead, hydrogen, copper, silver, gold
• potassium, sodium, calcium: reacts violently/readily with cold water
• magnesium, aluminium: reacts slowly with water, reacts readily with steam
• zinc, iron: reacts readily with steam
• very reactive metal + water ---> metal hydroxide + hydrogen

  less reactive metal + steam ---> metal oxide + hydrogen
• reactive metal + hydrochloric acid ---> salt + hydrogen
• the more reactive the metal, the faster the rate of effervescence
• reaction of lead and hydrochloric acid stops after a short while:

  insoluble layer of lead (II) chloride formed around lead metal, prevent further reaction
• metal oxide + hydrogen (reducing agent) ---> metal + steam

  metal oxide + carbon (reducing agent) ---> metal + carbon dioxide
• reactive metals (sodium, potassium, calcium, magnesium, aluminium): extracted by electrolysis -- need more energy to be broken down
• less reactive metals (zinc, iron, lead, copper, silver): extracted by reduction with carbon/hydrogen
• displacement: a more reactive metal will displace a less reactive metal from its compound
• A more reactive metal can displace a less reactive metal from its oxide.
• A more reactive metal can displace a less reactive metal from its solution.
• observations:

  • state colour change of solution
  • state colour change of solid
• A more reactive metal forms a more stable carbonate that needs to absorb more heat energy to decompose by heating.
• purpose of sanding aluminium:

  • aluminium reacts with oxygen in air
  • forming protective layer of aluminium oxide, preventing further reaction