Diamond and graphite
A form (allotrope) of pure carbon in which all the atoms are bonded to four others in a giant tetrahedral network structure which is very strong. Diamond is the hardest known natural substance, has a very high melting point and does not conduct electricity. and A form of pure carbon in which all the atoms are bonded to three others in giant sheets which can slide over each other. are different forms of the A substance made of one type of atom only. carbon. They both have giant structures of carbon The smallest part of an element that can exist., joined together by A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons.. However, their structures are different so some of their The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point. are different.
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Diamond
Structure and bonding
Diamond is a A structure in which very large numbers of atoms are joined together by covalent bonds in a regular network. in which:
- each carbon atom is joined to four other carbon atoms by strong covalent bonds
- the carbon atoms form a regular tetrahedral network structure
- there are no free Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.
Properties and uses
The rigid network of carbon atoms, held together by strong covalent bonds, makes diamond very hard. This makes it useful for cutting tools, such as diamond-tipped glass cutters and oil rig drills.
Like silica, diamond has a very high The temperature at which a solid changes into a liquid as it is heated. and it does not conduct electricity.
Graphite
Structure and bonding
Graphite has a giant covalent structure in which:
- each carbon atom forms three covalent bonds with other carbon atoms
- the carbon atoms form layers of hexagonal rings
- there are no covalent bonds between the layers
- there is one non-bonded - or Electrons that are not associated with a particular atom, eg in a metal, outer electrons can be free to move through the solid. - electron from each atom
Properties and uses
Graphite has delocalised electrons, just like metals. These electrons are free to move between the layers in graphite, so graphite can To allow electricity, heat or other energy forms to pass through. electricity. This makes graphite useful for A conductor used to establish electrical contact with a circuit. The electrode attached to the negative terminal of a battery is called a negative electrode, or cathode. The electrode attached to the positive terminal of a battery is the positive electrode, or anode. in batteries and for electrolysis.
The forces between the layers in graphite are weak. This means that the layers can slide over each other. This makes graphite slippery, so it is useful as a A lubricant is anything which reduces the friction between two surfaces..
Question
Explain why diamond does not conduct electricity and why graphite does conduct electricity.
Diamond does not conduct electricity because it has no charged particles that are free to move. Graphite does conduct electricity because it has delocalised electrons which move between the layers.