Metals & Acids

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Metals

Metals are malleable - they can be bent and shaped without breaking. This is because they consist of layers of atoms that can slide over one another when the metal is bent, hammered or pressed.

Metallic bonds

Metals form giant structures in which electrons in the outer shells of the metal atoms are free to move. The metallic bond is the force of attraction between these free electrons and metal ions. Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting and boiling points.

Delocalised electrons moving freely among an array of tightly packed metal atoms. (http://a.files.bbci.co.uk/bam/live/content/z7ydxnb/small)

Metals are good conductors of electricity and heat. This is because the delocalised electrons can move throughout the metal.

Metal extraction and the reactivity series

The method used to extract a metal from its ore depends upon the stability of its compound in the ore, which in turn depends upon the reactivity of the metal:

  • The oxides of very reactive metals, such as aluminium, form stable oxides and other compounds. A lot of energy is needed to reduce them to extract the metal.
  • The oxides of less reactive metals, such as iron, form less stable oxides and other compounds. Relatively little energy is needed to reduce them to extract the metal.

So, the method of extraction of a metal from its ore depends on the metal's position in the reactivity series.

Reactivity and extraction method

The table displays some metals in decreasing order of reactivity and the methods used to extract them.

MetalMethod Potassium Electrolysis Sodium Electrolysis Calcium Electrolysis Magnesium Electrolysis Aluminium Electrolysis (Carbon) (Non-metal) Zinc Reduction by carbon or carbon monoxide Iron Reduction by carbon or carbon monoxide Tin Reduction by carbon or carbon monoxide Lead Reduction by carbon or carbon monoxide (Hydrogen) (Non-metal) Copper Various chemical reactions Silver Various chemical reactions Gold Various chemical reactions Platinum Various chemical reactions

We can see from the table that reactive metals, such as aluminium, are extracted by electrolysis, while a less reactive metal, such as iron, may be extracted by reduction with carbon.

Because gold it is so unreactive, it is found as the native metal and not as a compound. It does not need to…

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