Why are covalent compounds poor conductors of electricity?

Covalent compounds are poor conductors of electricity because they do not have free electrons or ions to carry charge.

Covalent compounds, also known as molecular compounds, are formed when two non-metal atoms share electrons to achieve a full outer shell, creating a strong bond between them. This sharing of electrons results in a stable molecule with no charge. Because of this, there are no free electrons or ions available to carry an electrical charge, making covalent compounds poor conductors of electricity.

In contrast, ionic compounds, which are formed between a metal and a non-metal, do conduct electricity when dissolved in water or melted. This is because the ionic bonds break, releasing ions that are free to move and carry an electrical charge. Similarly, metals, which have a 'sea' of delocalised electrons, are also good conductors of electricity. These free electrons can move and carry an electrical charge through the metal.

However, covalent compounds lack these properties. In a solid covalent compound, the electrons are tightly held within each molecule and cannot move freely. Even when a covalent compound is dissolved in water or melted, it does not release ions that can carry an electrical charge. This is why substances like sugar or oil, which are covalent compounds, do not conduct electricity.

In summary, the lack of free electrons or ions in covalent compounds is the primary reason why they are poor conductors of electricity. This is a fundamental concept in understanding the different properties of ionic and covalent compounds.