Network solid

A network solid is a unique type of chemical substance. It is also known as a covalent network solid. These can be elements or chemical compounds. They are also called atomic crystalline solids or giant covalent structures. In these materials, atoms are linked by covalent bonds. These bonds create a continuous web throughout the entire material. Unlike many other substances, there are no individual molecules here. Instead, the entire crystal is considered one single macromolecule. This massive structure gives these solids very specific physical properties.

The way these solids work depends on their internal bonding. Atoms share electrons to form strong covalent bonds. In a network solid, these bonds extend through the whole object. This creates a continuous lattice of atoms. Some structures form a three-dimensional web. Diamond is a famous example of this type. It uses a continuous network of carbon atoms. Other solids use different building blocks. Quartz is a three-dimensional network of SiO2 units. These units are silicon dioxide.

Not all network solids are three-dimensional. Some form two-dimensional sheets. Graphite and the mica group are good examples. These materials consist of continuous sheets of atoms. The atoms within each sheet are covalently bonded. However, other types of bonds hold the layers together. This allows for different behaviors between the layers. For instance, deformation might be easier in certain directions. This happens when sheets flex or slide. This occurs without breaking the actual covalent bonds.

Most network solids are extremely hard. This hardness comes from the strong covalent bonds in the lattice. It is also very difficult to melt them. Melting requires enough energy to break these covalent bonds. This is different from many other solids. In those, melting only overcomes weaker intermolecular forces. Another type of structure is the glass. These are known as disordered network solids. They form when a melt cools very rapidly. The atoms do not have enough time to order themselves.

Electrical conductivity in these solids can vary greatly. It depends on the specific nature of the bonding. Some network solids use all electrons for sigma bonds. Diamond and quartz are examples of this. These materials are poor conductors. This is because they have no delocalized electrons. However, some solids can act like metals. Graphite can exhibit metal-like conductivity. This is due to the presence of delocalized pi bonds. Some solids may also use dopants to change this.

When these solids melt, their conductivity changes. In the liquid phase, electrical conductivity is usually low. This happens because the macromolecule consists of neutral atoms. Melting does not free up new charge carriers. This is a major difference from ionic compounds. Network solids are also very difficult to dissolve. They are generally insoluble in any solvent. This is because it is so difficult to solvate a macromolecule. The giant size of the structure prevents it from breaking apart easily.

Many different substances fall into this category. Some are common, like silicon and germanium. Others include boron nitride (BN) and aluminium nitride (AlN). Silicon carbide is another example. It is also called moissanite or carborundum. You can also find rhenium diboride (ReB2) in this group. Even alpha-tin, also called gray tin, is a network solid. These materials show how different atomic arrangements create different worlds. They connect the study of bonding to the study of physical properties.