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Giant covalent structures contain very many , each joined to adjacent atoms by . The atoms are usually arranged into giant regular - extremely strong structures because of the many bonds involved.

Properties of giant covalent structures

Very high melting points - this is because a lot of strong covalent bonds must be broken. Graphite, for example, has a melting point of more than 3,600°C.

Variable electrical conductivity - diamond does not electricity, whereas graphite contains free so it does conduct electricity. is a semi-conductor - it is midway between non-conductive and conductive.

Graphite is a form of in which the carbon atoms form . These layers can slide over each other, so graphite is much than diamond. It is used in pencils, and as a . Each carbon atom in a layer is joined to only three other carbon atoms. Graphite conducts electricity.

Diamond is a form of carbon in which each atom is joined to four other carbon atoms, forming a giant covalent structure. As a result, diamond is and has a high melting point. This explains why it is used in cutting tools. It does not conduct electricity.

Silica (or silicon dioxide ), which is found in , has a similar structure to diamond, so its properties are similar to diamond. It is hard and has a high melting point, but contains and atoms, instead of carbon atoms.

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BBC Bitesize - GCSE Chemistry (Single Science) - Covalent substances - Revision 4

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Giant covalent structures contain very many , each joined to adjacent atoms by . The atoms are usually arranged into giant regular - extremely strong structures because of the many bonds involved. Very high melting points - this is because a lot of strong covalent bonds must be broken.

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Giant covalent structures contain a lot of non-metal atoms, each joined to adjacent atoms by covalent bonds covalent bonds: A covalent bond between atoms forms when atoms share electrons to achieve a full outer shell of electrons.. The atoms are usually arranged into giant regular lattices lattice: A lattice is a regular grid-like arrangement of atoms in a material. - extremely strong structures because of the many bonds involved. The graphic shows the molecular structure of diamond and graphite: two allotropes allotropes: Allotropes are structurally different forms of an element. They differ in the way the atoms bond with each other and arrange themselves into a structure. Because of their different structures, allotropes have different physical and chemical properties. of carbon, and of silica (silicon dioxide).

Properties of giant covalent structures

Very high melting points - Substances with giant covalent structures have very high melting points, because a lot of strong covalent bonds must be broken. Graphite, for example, has a melting point of more than 3,600ºC.

[ Variable conductivity - Diamond does not conduct conduct: To allow electricity, heat or other energy forms to pass through. electricity. Graphite contains free electrons electrons: Sub-atomic particles, with a negative charge and a negligible mass relative to protons and neutrons. ] , so it does conduct electricity. Silicon is semi-conductive - that is, midway between non-conductive and conductive.

Graphite

Graphite is a form of carbon in which the carbon atoms form layers. These layers can slide over each other, so graphite is much softer than diamond. It is used in pencils, and as a lubricant lubricant: A substance used to reduce the friction between two solid surfaces.. Each carbon atom in a layer is joined to only three other carbon atoms. Graphite conducts electricity.

Diamond

Diamond is a form of carbon in which each carbon atom is joined to four other carbon atoms, forming a giant covalent structure. As a result, diamond is very hard and has a high melting point. It does not conduct electricity.

Silica

Silica, which is found in sand, has a similar structure to diamond. It is also hard and has a high melting point, but contains silicon and oxygen atoms, instead of carbon atoms.

The fact that it is a semi-conductor makes it immensely useful in the electronics industry: most transistors are made of silica.

Buckminsterfullerene

Buckminsterfullerene is yet another allotrope of carbon. It is actually not a giant covalent structure, but a giant molecule in which the carbon atoms form pentagons and hexagons - in a similar way to a leather football. It is used in lubricants.

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Covalent bonding - giant covalent structures

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Giant covalent structures contain a lot of non-metal atoms, each joined to adjacent atoms by covalent bonds covalent bonds: A covalent bond between atoms forms when atoms share electrons to achieve a full outer shell of electrons.. The atoms are usually arranged into giant regular lattices lattice: A lattice is a regular grid-like arrangement of atoms in a material.

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Challenge – Pick two giant covalent structures (collect the pictures) and compare them in terms of:

-Structure

-Bonds

-Properties

Do the same for two simple covalent molecules.

-Structure

-Bonds

-Properties

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However the structure of ... because...

The covalent bonds between... make the structure....

Comparing this structure to... because ...

In comparison to the properties of... because ...

Therefore the structure with the highest/ lowest... because ...

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The giant covalent structures of diamond, graphite and silicon dioxide and how they affect their physical properties