Why many covalently bonded molecular compounds are non-conductive:
* No free-moving charges: Covalent bonds involve sharing electrons between atoms. These electrons are localized within the bond and aren't free to move throughout the compound. This lack of free-moving charge carriers is essential for electrical conductivity.
* Weak intermolecular forces: Molecular compounds are typically held together by weak intermolecular forces like Van der Waals forces or hydrogen bonding. These forces are not strong enough to allow for the transfer of charge carriers.
Exceptions to the rule:
* Graphite: Although primarily held together by covalent bonds, graphite has a unique structure with delocalized electrons within its layers. These delocalized electrons can move freely, making graphite an excellent conductor of electricity.
* Polymers: Some polymers, like conductive polymers, have conjugated systems where electrons can move along the polymer chain, resulting in electrical conductivity.
* Dissolved ionic compounds: While covalent compounds themselves are often non-conductive, when dissolved in a solvent like water, some can dissociate into ions. These ions can then carry electrical current.
In summary:
Covalent bonding generally leads to non-conductivity due to the lack of free-moving charges. However, certain compounds, like graphite and conductive polymers, can exhibit conductivity due to specific structural features that allow for charge delocalization. Additionally, some covalently bonded compounds can become conductive when dissolved in a solvent, forming ions that can carry electrical current.
