Metals topic y9

• Properties of Metals


  • Good conductors of heat and electricity
  • Malleable (can be shaped)
  • Ductile
  • Shiny
  • Sonorous
  • Usually have high melting points
  • Strong
  • Dense
  • Hard
• Group 1 metals


  • Have low melting points
  • Low density
  • Soft
  • Highly reactive
• Transition metals


  • Have coloured compounds
  • Can form ions with different charges
  • Make good catalysts
• Alloy


  A mixture of metals. The atoms are of different sizes, disrupting the regular arrangement, so atoms can no longer slide over each other. Therefore an alloy is harder and stronger.
• Examples of alloys and their uses

  • Mild steel (iron and carbon) - used for construction
  • Stainless steel (iron, chromium and nickel) - used for cutlery
  • Brass (copper and zinc) - coins, pins of plugs, hinges
  • Bronze (copper and tin) - used to make statues and decorative objects
  • Aluminum alloys - low density, used in manufacture of aeroplanes
• Gold Carat


  Pure gold is 24 carat and is too soft. Gold used in jewelry etc is a mixture of gold with some silver/copper/zinc. % gold = carat/24 x100. Eg. 18 carat = 18/24 x100 = 75% gold.
• Corrosion is the reaction of a metal with oxygen in the air
• The more active the metal, the faster this takes place
• Aluminium reacts with oxygen in the air to form a protective coating of aluminium oxide
• Boiled water has less dissolved oxygen, so less corrosion
• Calcium chloride is a drying agent and absorbs water, keeping the metal dry
• Iron corrodes to form iron oxide (rust). As rust is flaky, this exposes more iron atoms which then corrode
• Salt water and acid rain speed up rusting
• Prevention of Rust


  • Coating iron - plastic or painting
  • Coating in a less reactive metal which does not corrode as quickly
  • Sacrificial protection - attaching a block of a more reactive metal which reacts instead of the iron
  • Galvanising - coating in zinc, which provides a protective layer and sacrificial protection
  • Alloys - reacting iron with another element to produce an alloy which does not corrode as quickly, e.g. stainless steel
• A more reactive metal will displace a less reactive metal from its compounds
• Metals above hydrogen in the reactivity series will displace hydrogen ions from acids
• The bigger the difference in reactivity, the more vigorous the reaction
• REDOX reaction


  A reaction in which oxidation and reduction both take place
• Formation and naming of Salts

  1. Metal + Acid -> Salt + Hydrogen

  2. The salt name is made up of the metal and the type of salt the acid forms
• Oxidation


  The loss of electrons
• Reduction


  The gain of electrons
• The greater the tendency of a metal to lose electrons, the more reactive the metal is
• Extraction of copper


  1. Copper ore is heated with carbon to remove oxygen (reduction)

  2. The carbon is oxidised in the process
• Traditional copper extraction requires lots of energy and produces large amounts of carbon dioxide
• Newer, more sustainable methods have been developed to extract copper from low grade ores or waste, reducing the need for mining</b>
• Mining causes destruction of habitats, noise, and visual pollution
• Newer extraction methods use less energy and produce less carbon dioxide
• What determines the order of reactivity (which reactions)?


  Metals are arranged in an order of reactivity based on how reactive or nonreactive they are with water, oxygen and hydrochloric acid.
• What is the order of reactivity?


  From most reactive to least reactive: Potassium, sodium, lithium, calcium, magnesium, zinc, iron, (hydrogen), copper, silver, gold.
• Metal + oxygen → ?

  metal oxide
• metal + water → ?


  metal hydroxide + hydrogen
• metal + steam →


  metal oxide + hydrogen
• metal + hydrochloric acid →


  metal chloride (salt) + hydrogen
• observations for the reaction: magnesium + oxygen → magnesium oxide


  - bright white flash

  - white powder (MgO)
• observations for the reaction: sodium + water → sodium hydroxide + hydrogen


  - fizzing due to H2 gas

  - sodium forms a ball, floats, then disappears
• observations for the reaction: iron + steam → iron(III) oxide + hydrogen


  n/a
• observations for the reaction: magnesium + hydrochloric acid → magnesium chloride + hydrogen


  fizzing due to H2 gas
• a more reactive metal will ________ a less reactive metal from its compound.

  displace
• colour and state of CuSO4:

  blue solution (aqueous)
• colour and state of Cu:

  pink-brown solid