Giant covalent structures of carbon
Allotropes are different forms of the same element in the same state. For example, diamond and graphite are allotropes of carbon. are different forms of an A substance made of one type of atom only. in the same physical state. 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 allotropes of carbon. They both consist of A structure in which very large numbers of atoms are joined together by covalent bonds in a regular network. in which very many carbon The smallest part of an element that can exist. are joined together by A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons.. However, their detailed structures and bonding differ, so their A description of the appearance of a substance or how it acts without involving chemical reactions. For example, state, melting point, conductivity, etc. are different.
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Diamond
Structure and bonding
Diamond is a giant A covalent substance is a molecule containing one or more covalent bonds (shared pairs of electrons). substance in which:
- each carbon atom is joined to four other carbon atoms by 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 three-dimensional arrangement 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.
Diamond has a very high melting point because a large amount of energy is needed to overcome the many strong covalent bonds. There are no electrons or other charged particles that are free to move so diamond does not conduct electricity.
Graphite
Structure and bonding
Graphite is a giant covalent substance in which:
- each carbon atom is joined to three other carbon atoms by covalent bonds
- the carbon atoms form a hexagonal layered network structure
- the layers have weak forces between them and can slide over each other
- each carbon atom has one non-bonding outer electron
- these non-bonding electrons are Electrons that are not associated with a particular atom, eg in a metal, outer electrons can be free to move through the solid., and are free to move
Properties and uses
Delocalised electrons are free to move through the structure of graphite, so graphite can To allow electricity, heat or other energy forms to pass through. electricity. This makes it 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 The decomposition (breakdown) of a compound using an electric current..
The layers in graphite can slide over each other because the forces between them are weak. This makes graphite slippery, so it is useful as a A lubricant is anything which reduces the friction between two surfaces..
Graphite is used to make the core or 'lead' in pencils because it is soft. The layers are easily rubbed off to leave a mark on paper.