1. C2: Structure, bonding and the properties of matter
Key Concepts

2. Types of bonding
Ionic bonding
Metal and non-metal atoms
Covalent bonding
Non-metal atoms only
Metallic bonding
Metal atoms only
All types of bonding involve changes in the number of electrons in the outer shells of atoms.

3. Examples include - Sodium Chloride, magnesium chloride.
Ionic compounds
One or more electrons are transferred from each metal atom to each non-metal atom.
The positive and negative ions are strongly attracted to each other. This electrostatic attraction is called an ionic bond.
Examples include - Sodium Chloride, magnesium chloride.

4. Properties of Ionic compounds
Example: sodium chloride.
Ionic substances:
Form crystals due to the regular arrangement of ions.
Conduct electricity when molten or in solution.
Are brittle
Are soluble
Have high melting and boiling points

5. Covalent Bonds
Bonding between non-metal atoms is called covalent bonding. This forms molecules.
The atoms share one or more outer electrons to gain a stable full outer shell.

6. Simple covalent structures
Oxygen, water and carbon dioxide are molecules. They have a simple structure because they only contain a few atoms. H O O O C
have low melting and boiling points;
are usually soft and brittle – they shatter when hit.
are usually insoluble in water but soluble in other solvents such as petrol;
cannot conduct electricity – there are no free electrons to carry an electrical charge.

7. Giant covalent structures
All the bonds are covalent, which means that giant covalent structures have a very high melting and boiling point.
This also means that almost all giant covalent structure are hard but brittle.

8. Metallic Bonds
Bonding within the atoms of a metal is metallic bonding.
Positive ions are held together by a sea of delocalised
Electrons.

9. Polymerisation
Heat
Pressure
Catalyst