The iodine bromide molecule, IBr, is an interhalogen compound. Assume that the molecular orbitals of IBr are analogous to the homonuclear diatomic molecule F2. (c) One of the valence MOs of IBr is sketched here. Determine whether each of the following statements about this orbital is true: i. This is an antibonding orbital. ii. The larger contribution is from the I atom. iii. The energy of the molecular orbital is closer in energy to the valence atomic orbitals of Br than to those of I.

Verified step by step guidance

1. Determine the type of molecular orbital: Antibonding orbitals are typically denoted with an asterisk (*). Check if the given molecular orbital has this notation.
2. Consider the atomic sizes and electronegativities: Iodine (I) is larger and less electronegative than bromine (Br). Larger atoms often contribute more to the molecular orbitals due to their larger atomic orbitals.
3. Compare the energies of the atomic orbitals: The energy of a molecular orbital is closer to the atomic orbital of the more electronegative atom. Since Br is more electronegative than I, its atomic orbitals are lower in energy.
4. Analyze the molecular orbital diagram: In a heteronuclear diatomic molecule like IBr, the molecular orbitals are not symmetrically distributed. The more electronegative atom (Br) will have a greater influence on the bonding and antibonding orbitals.
5. Evaluate the statements based on the above analysis: Use the information about antibonding characteristics, atomic contributions, and energy levels to assess the truth of each statement.

Key Concepts

Molecular Orbitals

Molecular orbitals (MOs) are formed by the linear combination of atomic orbitals (LCAO) from the constituent atoms in a molecule. They can be classified as bonding or antibonding orbitals, where bonding orbitals stabilize the molecule and antibonding orbitals destabilize it. Understanding the nature of these orbitals is crucial for predicting the stability and reactivity of molecules.

Electronegativity and Atomic Contributions

Electronegativity refers to the tendency of an atom to attract electrons in a bond. In interhalogen compounds like IBr, the contributions of each atom to the molecular orbitals depend on their electronegativities. Since iodine (I) is less electronegative than bromine (Br), the molecular orbital may have a larger contribution from the iodine atom, affecting the overall bonding characteristics.

Energy Levels of Atomic and Molecular Orbitals

The energy levels of molecular orbitals are influenced by the energy levels of the atomic orbitals from which they are derived. In IBr, the energy of the molecular orbitals can be compared to the valence atomic orbitals of iodine and bromine. Typically, the energy of a molecular orbital will be closer to that of the atomic orbital of the more electronegative atom, which in this case is bromine.