The Properties of Giant Covalent Structures

Covalent bonds form between non-metallic atoms through the sharing of one or more pairs of electrons to complete their outer shells. There are two main types of structures with covalent bonds:

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• Giant covalent structures

• Simple covalent structures

Giant Covalent Structures are large networks of atoms bonded together by covalent bonds. These structures are not defined by a specific number of atoms. However, if the structure includes atoms from two or more elements, the proportions will stay the same regardless of the size of the structure. This means that giant covalent structures have continuous and repeating patterns.

Silicon Dioxide

Let’s look at silicon dioxide (silica) as an example. This giant covalent structure is the main component of sand.

Although it is made up of many silicon and oxygen atoms bonded covalently, it has a basic formula of SiO₂. This formula indicates a ratio of one silicon atom to every two oxygen atoms throughout the structure, regardless of its size.

Properties of Giant Covalent Structures

Giant covalent structures:

• remain solid at room temperature.

• have very high melting points because melting these structures involves breaking many strong covalent bonds, which requires a lot of energy. Boiling them requires even more energy due to the need to break additional bonds.

• generally, have no overall charge and do not conduct electricity because they lack free electrons. However, graphite is an exception to this rule.

• are insoluble in water due to the strength of the covalent bonds within their structure, which water molecules cannot easily disrupt.

Graphite is one of the few giant covalent structures that can conduct electricity. Each carbon atom in graphite forms three covalent bonds with other carbon atoms, creating layers of hexagonal structures. This leaves one electron from each carbon atom free to move within the layers, allowing graphite to conduct electricity.