Based on the molecular orbital theory, what can we say about the first ionization energy for H₂ molecule? A) It is lower than the first ionization energy of H atom. B) It is higher than the first ionization energy of H atom. C) It is about the same as the first ionization energy of H atom.

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The molecular orbital theory suggests that when atoms form a molecule, their atomic orbitals combine to form molecular orbitals. In the case of a hydrogen molecule (H2), the bonding molecular orbital is lower in energy than the atomic orbitals of the individual hydrogen atoms. However, the question refers to the first ionization energy, which involves removing an electron from the highest occupied molecular orbital (HOMO). For H2, this would be the bonding molecular orbital. Removing an electron from a molecule generally requires more energy than from an isolated atom because of the additional stability gained through bonding. Therefore, the first ionization energy of H2 (or any molecule formed by hydrogen with another atom, assuming the molecule is more stable than the isolated hydrogen atom) would be higher than that of a hydrogen atom alone.

Based on the Molecular Orbital Theory, What Can We Say