Molecular orbitals

Definition

Molecular orbitals are mathematical functions that describe the wave-like behavior of electrons in a molecule, formed by the combination of atomic orbitals from different atoms. These orbitals can be occupied by electrons and play a crucial role in determining the chemical properties and behavior of molecules, including bonding and electronic structure.

5 Must Know Facts For Your Next Test

1. Molecular orbitals can be classified as bonding, antibonding, or non-bonding, with bonding orbitals stabilizing the molecule and antibonding orbitals destabilizing it.
2. The Pauli Exclusion Principle states that each molecular orbital can hold a maximum of two electrons with opposite spins.
3. Molecular orbital theory allows for the explanation of phenomena such as resonance and the magnetic properties of molecules based on their electronic configurations.
4. Electrons in molecular orbitals can be delocalized over several atoms, which can affect the stability and reactivity of the molecule.
5. The energy levels of molecular orbitals are determined by the energies of the atomic orbitals involved and their relative interactions during molecular formation.

Review Questions

• How do molecular orbitals differ from atomic orbitals, and what is their significance in chemical bonding?
  • Molecular orbitals differ from atomic orbitals in that they represent the combined wave functions of electrons from two or more atoms rather than from a single atom. They are significant in chemical bonding because they help explain how atoms bond together by providing regions where electrons are likely to be found. This understanding allows chemists to predict the stability and reactivity of molecules based on whether electrons occupy bonding or antibonding molecular orbitals.
• Discuss the implications of electron delocalization in molecular orbitals on a molecule's stability and reactivity.
  • Electron delocalization in molecular orbitals leads to increased stability for certain molecules, especially those with resonance structures. When electrons are spread out over multiple atoms instead of being localized between two atoms, it lowers the overall energy of the molecule, making it more stable. This delocalization also impacts reactivity, as molecules with delocalized electrons may participate in different chemical reactions compared to those with localized electron pairs, influencing how they interact with other substances.
• Evaluate how molecular orbital theory can explain the magnetic properties of diatomic oxygen and relate this to its molecular orbital configuration.
  • Molecular orbital theory explains the magnetic properties of diatomic oxygen by revealing that it has unpaired electrons in its molecular orbitals. Specifically, when we fill its molecular orbitals according to Aufbau's principle, we find that two electrons occupy the antibonding π* orbital. This results in two unpaired electrons, which is responsible for its paramagnetism. The presence of unpaired electrons means that diatomic oxygen will be attracted to a magnetic field, which aligns with observations that show oxygen's magnetic behavior.

Related terms

atomic orbitals: Regions in an atom where there is a high probability of finding electrons, characterized by specific shapes and energy levels.

bonding orbital: A type of molecular orbital formed when atomic orbitals combine in such a way that increases electron density between two nuclei, promoting chemical bonding.

antibonding orbital: A molecular orbital that results from the destructive interference of atomic orbitals, leading to a decrease in electron density between the nuclei and thus destabilizing the molecule.