Difference between Bonding and Antibonding Molecular Orbitals
Molecular orbitals are formed when atomic orbitals of atoms combine in order to form a covalent bond. Bonding and antibonding molecular orbitals are two types of these molecular orbitals. These orbitals have different properties and play different roles in the bonding and stability of molecules.
Bonding Molecular Orbitals
Bonding molecular orbitals are formed by the constructive interference of atomic orbitals. This means that the atomic orbitals overlap in such a way that their wavefunctions add up to form a new, stronger orbital. Electrons in bonding molecular orbitals are attracted towards the two nuclei, and the bond energy is lower than that of the isolated atoms.
In other words, when the phase of atomic orbitals is the same, the electron density is localized between the two nuclei, and this results in a stronger bond. Bonding molecular orbitals are usually lower in energy than atomic orbitals, and their energies increase as the number of atoms involved in the bond increases.
Antibonding Molecular Orbitals
Antibonding molecular orbitals, on the other hand, are formed by the destructive interference of atomic orbitals. This means that the atomic orbitals overlap in such a way that their wavefunctions subtract from one another, resulting in a node between the two nuclei. Electrons in antibonding molecular orbitals are repelled away from the two nuclei, and as a result, the bond energy is higher than that of the isolated atoms.
In other words, when the phase of atomic orbitals is opposite, the electron density is not localized between the two nuclei, and this results in a weaker bond. Antibonding molecular orbitals are usually higher in energy than atomic orbitals, and their energies decrease as the number of atoms involved in the bond increases.
Conclusion
In conclusion, bonding and antibonding molecular orbitals have different properties and play different roles in the bonding and stability of molecules. Bonding molecular orbitals result in stronger bonds, while antibonding molecular orbitals result in weaker bonds. Understanding these orbitals can help us predict the stability and reactivity of molecules, and can provide insights into chemical reactions and molecular properties.
Table difference between bonding and antibonding molecular orbitals
| Bonding Molecular Orbitals | Antibonding Molecular Orbitals | |
|---|---|---|
| Definition | Electron orbitals that contribute to the stability of a molecule by constructive interference of wave functions. | Electron orbitals that contribute to the instability of a molecule by destructive interference of wave functions. |
| Formation | Formed by adding wave functions of atomic orbitals that are in phase to produce a resultant wave function with increased electron density at the bond region. | Formed by subtracting wave functions of atomic orbitals that are out of phase to produce a resultant wave function with a node at the bond region, resulting in decreased electron density and no bonding. |
| Energy | Lower in energy than the constituent atomic orbitals, leading to the stability of the molecule. | Higher in energy than the constituent atomic orbitals, leading to the instability of the molecule. |
| Electron Distribution | Electron density between the two positively charged nuclei, leading to the formation of a bond. | Electron density outside the region between the two nuclei, leading to no bond formation. |