Paper 1 - 2/2 Flashcards
Give examples of giant covalent structures.
Diamond, graphite, graphene and silica (silicon dioxide).
Describe the structure of diamond.
Each carbon atom forms 4 covalent bonds.
This forms a very rigid structure.
This is the hardest natural material - used for drill tips.
Has very high melting point.
It does not conduct electricity.
Describe the structure of graphene.
The carbon atoms each have 3 covalent bonds, as for graphite.
Joined in hexagons.
1 layer thick.
Can conduct electricity as they have free electrons (delocalised electrons).
Describe the structure of graphite.
Each carbon atoms forms 3 covalent bonds.
This forms a layers of hexagonal rings.
Layers are free to SLIDE over each other as there are no covalent bonds between layers.
Has high melting point.
It does conduct electricity and thermal energy because there is one delocalised electron on EACH carbon atom.
Describe the structure of fullerenes.
Molecules of carbon atoms with hollow shapes.
Based on hexagonal rings of carbon atoms.
Rings may contain FIVE 5 or SEVEN 7 carbon atoms.
First discovered was C₆₀ - Buckminsterfullerene.
Can be used for drug delivery, as lubricants and as catalysts.
Describe the structure of fullerenes - nanotubes.
Nanotubes are CYLINDRICAL fullerenes.
High tensile strength.
High electrical conductivity.
High thermal conductivity.
Used for reinforcing materials, e.g. tennis rackets.
Name the process of changing from a solid to a gas
Sublimation.
Give five properties of simple molecular substances.
Covalent bonds within a molecular are very strong, electrostatic forces.
Attraction between simple molecular substances are very weak!
Melting points and boiling point are LOW.
At room temperatures, most a liquid or gases.
They DO NOT conduct electricity, as they HAVE NO IONS.
Give four properties of giant covalent structures.
All atoms are bonded by STRONG covalent bonds.
They are very high boiling and melting point.
Do NOT conduct electricity , as there are NO IONS.
Usually insoluble in water.
