Conductors

• To conduct, charged particles must be present and these charged particles must be free to move.
• There are two types of conductors:
  • Elements which conduct in both solid and liquid because their outer shell electrons are mobile g. metals
  • Electrolytes conduct because they contain positive and negative ions. In electrolytes, the mobile ions carry the current under the influence of an electric field, and the electrolyte is decomposed/discharged as the ions gain or lose electrons at the electrodes g. Sodium Chloride solution

Allotropes – different forms of the same element.

Allotropy – when an element can exist in more than one physical form in the same state

Giant covalent structures – structures with a network of covalent bonds throughout it. They take a lot of energy to break and have high boiling and melting points.

	Diamond	Graphite	Silicon Dioxide (Silica)
Structure
Bonding	Each carbon atom has four covalent bonds with other carbon atoms	Each carbon atom has three covalent bonds with other carbon atoms. Van der Waal’s forces hold the layers together.	Each silicon atom has four covalent bonds with oxygen atoms.
Arrangement	Carbon atoms link together to form a giant lattice structure	Arranged in hexagons and are arranged in layers on top of each other. Electrons move throughout layers	Atoms link together to form giant lattice structure
Prop.	Does not conduct electricity, high melting point, insoluble	Conducts Electricity, high melting point, insoluble	Does not conduct electricity, high melting point, insoluble
Look	A hard, colourless, transparent crystal which sparkles in light	A soft dark grey, shiny solid with a slippery feel	A hard, colourless, transparent crystal which sparkles in light (Quartz)
Use	Jewellery, Glass Cutters, Polishers	Pencils, Electrodes, Lubricants	Cement