Which of the following statements regarding valence-bond method is not true?
Which of the following statements regarding valence-bond method is not true?
In the valence-bond method, the molecule is considered to be the collection of atoms and then interactions between different atoms are considered
For a molecule to be stable, the electrostatic attractions must predominate over the electrostatic repulsions
The potential energy of a diatomic molecule is less than the sum of corresponding energies of free atoms
The net force of attraction acting on the atoms in a molecule is greater than that of repulsion
Solution
1. In the valence-bond method, the molecule is considered to be the collection of atoms and then interactions between different atoms are considered.
- This statement is true. The valence-bond method focuses on the interactions between atomic orbitals as they combine to form chemical bonds, effectively treating the molecule as a collection of interacting atoms.
2. For a molecule to be stable, the electrostatic attractions must predominate over the electrostatic repulsions.
- This statement is true. For a molecule to be stable, the attractive forces between the positively charged nuclei and negatively charged electrons must outweigh the repulsive forces between like charges (e.g., electron-electron and nucleus-nucleus repulsions).
3. The potential energy of a diatomic molecule is less than the sum of corresponding energies of free atoms.
- This statement is true. When atoms form a molecule, the potential energy of the bonded state is typically lower than the sum of the energies of the separate atoms. This energy difference is what makes the molecule stable compared to the separate atoms.
4. The net force of attraction acting on the atoms in a molecule is greater than that of repulsion.
- This statement is not necessarily true. The net force acting on the atoms in a molecule includes both attractive and repulsive components. The stability of the molecule is a result of the balance between these forces, where the total potential energy is minimized when the attractive forces roughly balance the repulsive forces. Thus, while the molecule is stable, it does not imply that the net force of attraction is always greater than the net force of repulsion; rather, the total potential energy is minimized due to this balance.
^