Intermolecular Bonding
- Simple molecular structures consist of molecules that contain just a few atoms
- Examples include carbon dioxide and methane
- These types of structures have:
- Covalent bonds- found between the atoms
- Intermolecular bonds / forces- found between the molecules
- Covalent bonds are very strong in comparison to intermolecular bonds
Diagram to show the difference between covalent and intermolecular bonds
Covalent bonds are between atoms, intermolecular bonds are between molecules
Linking the Bonding & Properties
- They have low melting and boiling points:
- This is due to the intermolecular bonds being weak so they require little energy to overcome
- As the molecules increase in size, the melting and boiling points generally increase because the strength of these intermolecular bonds increases and so more energy is needed to break them
- They are poor conductors of electricity (even when molten)
- There are no free ions or electrons to move and carry the charge.
- Most covalent compounds do not conduct at all in the solid state and are thus insulators
- Common insulators include the plastic coating around household electrical wiring, rubber and wood
Diagram of a wire
Covalent molecules in insulators do not allow a flow of charge
Exam Tip
Remember: When explaining their low melting and boiling point, it is not the covalent bonds between the atoms which are broken, but the weak intermolecular bonds.
