Why do covalent compounds generally have low melting and boiling points?

Question

Question

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RRB JE CE 22 Apr 2025 Shift 1 CBT 2 Official Paper

Answer 1

The correct answer is They have weak intermolecular forces.

Key Points

Covalent compounds are formed by the sharing of electrons between atoms.
These compounds usually have low melting and boiling points due to the presence of weak intermolecular forces.
The individual molecules are held together by Van der Waals forces or dipole-dipole interactions, which are much weaker than ionic or metallic bonds.
As a result, it requires less energy to overcome these forces, leading to lower melting and boiling points.
Examples of covalent compounds with low melting and boiling points include water (H₂O), methane (CH₄), and carbon dioxide (CO₂).

Additional Information

Metallic Bonds
- Metallic bonds are characterized by a 'sea of electrons' that are free to move around.
- This type of bonding leads to high melting and boiling points as the bonds are strong and require more energy to break.
Electrostatic Forces
- Electrostatic forces are the forces between charged particles, such as ions.
- In ionic compounds, these forces are very strong, resulting in high melting and boiling points.
Rigid Lattice Structure
- A rigid lattice structure is typically found in ionic compounds and some covalent network solids like diamond.
- This structure contributes to high melting and boiling points due to the strong bonds that hold the lattice together.