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AQA GCSE Chemistry Structure

Structure

This page covers the following topics:

1. Ionic compounds
2. Small molecules
3. Giant covalent structures
4. Metals and alloys

Ionic compounds form giant crystalline ionic lattices, held together by the strong electrostatic forces of attraction between the oppositely charged ions. The stronger this attraction, the higher the melting point of the ionic compound. If the ions in the lattice are free to move then the compound can conduct electricity.

Ionic compounds

Small molecules are held together by strong covalent bonds, but weak intermolecular interactions so they're usually gases or liquids at room temperature.

Small molecules

Some elements form giant covalent lattices which are large structures with multiple atoms joined together by covalent bonds. These lattices have exceptionally high melting and boiling points. The layout of the atoms in these structures also determines the physical properties of the compound, ie. hardness, density.

Giant covalent structures

Metals form large structures held together by metallic bonding. Pure metals are usually very soft and malleable, so different metallic elements are mixed to form alloys with preferable properties.

Metals and alloys

1

Which giant covalent structure is the hardest naturally occuring substance on Earth?

Which giant covalent structure is the hardest naturally occuring substance on Earth?

2

What is an 'alloy'?

What is an 'alloy'?

3

Order these ionic compounds in order of increasing melting point, CaO, KCl and MgFβ‚‚.

Order these ionic compounds in order of increasing melting point, CaO, KCl and MgFβ‚‚.

4

Draw a dot-and-cross diagram showing the covalent bond formed in Hβ‚‚.

Draw a dot-and-cross diagram showing the covalent bond formed in Hβ‚‚.

5

Draw a dot-and-cross diagram of methane, CHβ‚„.

Draw a dot-and-cross diagram of methane, CHβ‚„.

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