This blog is created solely to record down discoveries made in my pursuit for the truth behind this world.

Simple molecular structure

In a simple molecular substance, the molecules in the substance are held together by weak intermolecular forces. Very little energy is required to overcome these weak intermolecular forces and separate the molecules from each other. Hence, simple molecular substances have low melting and boiling points. They are volatile.

Simple molecular compounds do not conduct electricity as they do not possess mobile ions or electrons within their structure.

Macromolecular structure

In the case of a diamond:

Diamond is hard as it has a rigid network of repeating units of tetrahedrally arranged carbon atoms joined by strong covalent bonds. These atoms do not move out of their position when force is applied due to these strong covalent bonds that exist among them.

Diamond has a high melting point as diamond has a macromolecular structure comprising of a network of repeating units of tetrahedrally arranged carbon atoms held together by strong covalent bonds. Since a lot of energy is required to overcome these strong covalent bonds and change diamond from the solid to liquid state, Diamond has a high melting point.

Diamond does not conduct electricity as all the valence electrons of the tetrahedrally arranged carbon atoms are used for bonding. Hence there are no mobile electrons that move through the structure, disallowing diamond to conduct electricity.

Uses of diamond: Gemstones in jewellery, tips of drills.

In the case of graphite:

Graphite is soft and slippery as the layers of hexagonally arranged carbon atoms are held by weak intermolecular forces, and these layers can slide over each other.

Graphite has a high melting point as the hexagonally arranged carbon atoms within each layer are held together by strong covalent bonds. A lot of energy is required to overcome these strong covalent bonds and to change graphite from the solid to the liquid state. Hence graphite has a high melting point.

Graphite can conduct electricity as each carbon atom has a delocalized mobile electron that is not used to form covalent bonds. These mobile electrons are able to move along the layers from one carbon atom to the other and hence graphite is a good conductor of electricity.

Uses of graphite: lubricate machine parts that contain rubber, pencil lead, brushes for electric motors.

Labels: Chemistry, Covalent Bonding