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Molecules in the air

Dry air contains non-metal elements eg. nitrogen, oxygen argon. Air also contains small amounts of non-metal compounds eg. carbon dioxide and water vapour. The atoms in thre molecules are held together with covalent bonds because covalent bonds occur between non-metals:

Covalent bonds form when atoms share a pair of electrons to gain a full outer shell. The atoms are held together because there is electrostatic attraction between the nuclei of the atoms and the electrons shared between them. Eg. In water hydrogen atoms and a oxygen atom share electrons to gain full outer shells.

For most covalent molecules, the forces between molecules are weak but the forces within the molecules (covalent bonds) are strong. Therefore, they are often gases due to there low boiling/ melting points as they are small molecule and little force is needed to overcome the forces between molecules. They don't conduct electricity as molecules are charged.

Most non-metal elements and most compounds between non-metal elements are molecular

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Ionic cystals

The hydrosphere is mostly water with some dissolved compounds called salts.

These salts contain ions arranged in a regular lattice. Ionic bonds are formed because there is a metal and a non metal. The strong ionic bonds mean they have a high boiling/ melting points. They dont conduct electricity unless dissolved or molten because ions are fixed and cannot move.

In the formula for an ionic compound the number of positive charges balance the negative charges eg.Mg2+ and Cl- make MgCl2. some ions, eg. sulphate, contain groups of atoms. This is called a molecular ion.

Solutions of some ionic compounds may form a percipitate. Percipitates form when an insoluble solid is made in the reaction. For example most metal hydroxides are insolable as is silver chloride from the reaction of silver ions and chloridre ions

Ionic equations with state symbols show what happens what percipitates form:

Cu2+ (aq) + 2OH- (aq) --> Cu(OH)2 (s)

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Giant molecules and metals

The lithosphere is made of rocks and minerals. Minerals are solids with atoms or ions arranged in a lattice. The most abundant elements in the lithosphere are

  • oxygen
  • silicon     (mostly as silicon dioxide another giant covalent compound)
  • aliminium

Rocks that contain metal minerals are called ores. Some ores containe metal oxides.

Diamond and graphite are minerals, both of which are composed of carbon atoms. Diamonds are very hard, have high melting and boiling points, do not conduct electricity and are insolubal because of strong ionic bonds

Like diamond, graphite has a giant molecular structure. However, graphite contains layers of carbon atoms. The layers slide over each other easily because there are only weak forces between them, making graphite slippery. Graphite contains electrons which can inderpendantly move through the graphite, carrying charge from place to place and allowing graphite to conduct electricity.

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Water and salts in the hydrosphere

Electostatic attraction between partial charges produce inter molecular forces produce inter molecular charges. These are no as strong as ionic or covalent bonds

Water is a good solvent for salt

solvent + solute --> solution

water + salt --> solution

salts dissolve as oxygen has a slight negative charge so it pulls out the sodium from the sodium chloride one at a time

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Extracting metals from ores

Methods of extraction:

  • Some elements are found naturally as metals because they are so unreactive eg. gold
  • Some elements are extracted by reduction as carbon is more reactive so displaces the metal. The reduction is done in a blast furnace. There is equal contact between the metal oxide and the charcol. Oxygen released from the iron oxide will react with the carbon to create carbon dioxide. The metal is left to cool and solidify.
  • Some elements are extracted by electrolysis when they are more reactive than carbon eg. aliminium. Eletrolysis is the splitting of currents using an electrical current.

Bauxite= alliminium ore. Sodium hydroxide is added to the bauxite to remove any impuritities. The bauxite is made molten by using heat to break the ionic bonds. The aliminium goes to the negative electrode because it is positive and it gains 3 electrons in an oxidation reaction. The oxygen goes to the negative electrode because it is positive and looses 2 electrons in a reduction reaction. It them reacts with another oxygen to become a diatomic gas

  • Al3+ + 3e- --> Al
  • O2- + O + e-      O + O --> O2
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Issues with extracting metals

Is there a good supply of ore?

How can the ore be reduced? Reduction, electrolysis

Impact on the environment? CO2 is produced, noise pollution, dust production , waste rock, leaves large holes left in the ground, caves may cave in.

Energy cost? electricity is need, too expensive

Production? waste may contain traces of toxic materiels such as lead and mercury

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Calculating molecular mass

Calculate total mass of metal   52 x 2 = 104

Calculate total mass of mineral   104 + 56 + (16 x 4) = 224

Calculate percent  104/224 x 100 = 46%

Turn percent into grams   100grams = 46grams

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Metallic bonds occur between two metals. They are strong but weaker than covalent and ionic. All the ions are positive

The attraction between the positive charge on the metal atoms and negative charges are able to move and so can conduct electricty. It also means that metal are malleable as positive ions can move into space and slide past each other forming new shapes


The atom gives up an electron for a full outer shell. the electrons are attracted to the ions so they are held together. Ions are not repelled as electrons between.

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The life of metals

  • mining the ore
  • ore is crushed to increase the surface area
  • purifying of the metal
  • extracting the mineral using electrolysis
  • metal ingot
  • shaping the metal
    • recycle scrap metal
    • metal ingot
  • manufacturing products from the metals
    • recycle scrap metal
    • metal ingot
  • end of useful life
    • seperate and recycle waste metal
    • metal ingot
  • rubbish to waste tip
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