TRIPLE:1.45 explain how the uses of diamond and graphite depend on their structures, limited to graphite as a lubricant and diamond in cutting

Diamond and Graphite Part II

Diamond is very hard and abrasive (strong covalent bonds that are difficult to break and it does not conduct electricity as there is no delocalised electrons. This makes it suitable to be used for cutting tools on drills because it is so abrasive. Diamond is also used for jewellery because shiny rocks seem attractive to humans.

Graphite is soft and slippery (forces of attraction between the layers are weak so the layers easily slide over one and another so can be easily separated). Graphite also conducts electricity, as there is a fourth electron that is delocalised between the layers and are free to move parallel to the layers. It is used as a lubricant because it is slippery and soft and because it is an conductor it is perfect for electrodes for electrolysis.

TRIPLE: 1.44 draw diagrams representing the positions of the atoms in diamond and graphite

Diamond and graphite Part I



As you can see from the diagram, the diamond structure, which is made up from carbon atoms are joined to 4 other carbon atoms, this is an example of a giant covalent structure.

Graphite is another example of a giant covalent structure made out of carbon atoms. Each carbon atom is joined to 3 other carbon atom. It is an example of a lattice, where weak forces exist between each layer.

1.43 explain the high melting and boiling points of substances with giant covalent structures in terms of the breaking of many strong covalent bonds

Giant covalent structures

Some substances are made up of millions of atoms covalently bonded together to form a giant structure. These substances have high melting and boiling points, because when melting or boiling it, you are not separating inter-molecular bonds between the atoms, but the inter-molecular bonds that keep the molecule together. There are a lot of these, therefore they have high melting and boiling points.