Bonding is the word used to describe how the particles are held together in compounds.

There are three main types of chemical bonding. It is easy to work out which type of bonding will occur by looking at the elements involved!

1. Ionic Bonding:

This type of bonding occurs between metal elements and non-metal elements.
Examples include sodium chloride (NaCl) and Calcium oxide (CaO).
Compounds with ionic bonds are sometimes called salts.

2. Covalent Bonding:

This type of bonding occurs between two or more non-metal elements.
Examples include water (H2O), and Chlorine gas (Cl2)
Compounds with covalent bonds are called molecules.

We hope you have heard of these two types of bonding - you may not have heard of the third one!

3. Metallic Bonding:

This type of bonding occurs in metal elements.
Examples include copper and iron.
Metals do not form compounds with other elements, but mixtures of metals can be made. These mixtures are called alloys, and alloys also contain metallic bonds.

Checkpoint.

Q1. Look at the ten compounds below, and decide whether the bonding will be ionic, covalent or metallic. You may need a periodic table to help you decide which elements are metals and non-metals.

a. potassium chloride (KCl)
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b. carbon dioxide (CO2)
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c. hydrogen chloride (HCl)
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d. aluminium
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e. iron oxide (Fe2O3)
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f. magnesium iodide (MgI2)
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g. fluorine gas (F2)
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h. brass (a mixture of zinc and copper)
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i. ammonia (NH3)
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j. calcium carbonate (CaCO3)
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Q2. Which of the compounds above are molecules?
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