Question

(a) If you combine two atomic orbitals on two different atoms to make a new orbital, is this a hybrid orbital or a molecular orbital? (b) If you combine two atomic orbitals on one atom to make a new orbital, is this a hybrid orbital or a molecular orbital? (c) Does the Pauli exclusion principle (Section 6.7) apply to MOs? Explain.

Short answer

(a) Combining two atomic orbitals from different atoms results in a molecular orbital. (b) Combining two atomic orbitals on the same atom results in a hybrid orbital. (c) The Pauli Exclusion Principle applies to molecular orbitals as well, ensuring that each molecular orbital can accommodate a maximum of two electrons with opposite spins.

Step-by-step solution

Question (a)

When combining two atomic orbitals from different atoms, the resulting orbital is known as a molecular orbital. Molecular orbitals are formed when the wave functions of atomic orbitals from different atoms interact, resulting in a new orbital that may be bonding or antibonding, depending on the phase of the atomic orbitals involved.

Question (b)

Combining two atomic orbitals on the same atom results in a hybrid orbital. Hybridization occurs when atomic orbitals on the same atom mix to form new orbitals with different shapes and energies. This allows the atom to form stronger bonds with other atoms. Examples of hybrid orbitals include sp, sp2, and sp3 orbitals, which are formed by mixing s and p orbitals on the same atom.

Question (c)

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers, which also implies that each atomic orbital can accommodate a maximum of two electrons with opposite spins. This principle also applies to molecular orbitals because molecular orbitals are still occupied by electrons with spin. The exclusion principle ensures that each molecular orbital can also accommodate a maximum of two electrons with opposite spins, just like atomic orbitals.