Giant Covalent Structures

Definition

A giant covalent structure is a large network of atoms joined together by covalent bonds where thousands of atoms can be linked together in this way.

Covalent bonds are formed when two non-metals share electrons.
In a giant covalent structure, many atoms are linked together by shared pairs of electrons to form a large network or lattice structure.
Each atom is joined to several others, leading to the formation of a giant structure.

High melting and boiling points: Due to multiple strong covalent bonds, these structures require a lot of energy to be broken down. This results in high melting and boiling points.
Hardness: Giant covalent structures are generally hard. For example, diamond, a form of carbon, is one of the hardest known materials.
Conductivity: Most giant covalent structures do not conduct electricity as they do not have delocalised electrons. However, graphite, which is a form of carbon, does conduct electricity as it has one layer of delocalised electrons.
Solubility: These structures are usually insoluble in water and other common solvents.
Density: Giant covalent structures can have a high or low density depending on the specific structure and arrangement of atoms.

Certain elements exist as giant covalent structures. These include carbon in the form of diamond and graphite, and silicon dioxide, more commonly known as silica or quartz.
Diamond and graphite, although both forms of carbon, have very different properties due to their different structures.
Diamond has a rigid network structure with each carbon atom joined to four other carbon atoms, forming a very hard, transparent substance.
Graphite, on the other hand, consists of layers of carbon atoms with each atom only joined to three other carbon atoms, allowing the layers to slide over each other. This makes graphite soft and slippery.
Silicon dioxide, or silica, is a ubiquitous component of the earth’s crust and has a complex and largely variable structure that includes a range of crystalline forms and an amorphous form.

These structures are stable due to the strong covalent bonds and large amounts of energy required to break them.
The shared pairs of electrons between atoms also contribute to this stability as they fill the outer electron shells of the atoms involved.

The formation of a giant covalent structure is exothermic as it releases energy, primarily because the energy required to form covalent bonds is less than the energy released by the formation of these bonds.

Common examples of giant covalent structures include diamond, graphite, silica, silicon, and boron.