Properties of covalent molecule

1. Properties of covalent molecule

2. Melting and boiling points • When a substance melts the particles break out of their position (the intermolecular forces have been overcome). • For small molecules, the intermolecular forces are weak and therefore its does not take a lot of energy to overcome these forces, making melting and boiling points low

3. Electrical conductivity • In Covalent molecular substances the electrons are localised and therefore cannot move

4. Hardness and softness • The intermolecular forces in Covalent molecular substances determines whether they will be hard or not . • Most covalent molecular substance are soft. • Because intermolecular forces are quite weak covalent molecular substances tend to be gases and liquids

5. Chemical reactivity • Covalent network lattices and covalent layer lattices are very unreactive because they have such strong bonds • Small molecular substances are more reactive because their bonds are not as strong.

6. Covalent network lattices and covalent layer lattice

7. 3 Different types of Carbon • Charcoal, diamond and graphite are different physical forms of carbon , these are called allotropes of carbon.

8. Covalent Network Lattice • The carbon in Diamond is bonded very strongly in a 3D lattice making it hard and crystalline with a very high melting point. They are very unreactive because of strong bonds. Do not conduct electricity because there are no free moving electrons.

9. Other examples of covalent network lattices • Silicon dioxide also called silica is found in quartz

10. Covalent layer lattices • In graphite each carbon is covalently bonded to three other carbon atoms. This forms layers of hexagonal rings. The forces between layers are weak and layers can slide over one another so graphite is soft. Graphite has one electron from each carbon delocalised and therefore these are able to carry electric current. Weak intermolecular bonds