Molecular Orbital Theory Concepts

Professor Dave revisits molecular orbital theory, contrasting it with valence bond theory. He explains the basics of both theories, focusing on molecular orbital theory's ability to predict electron arrangements through wave functions and interference. The tutorial covers constructive and destructive interference, molecular orbital diagrams, and the phenomenon of s-p mixing, which affects orbital energies. The video aims to deepen understanding of molecular orbitals and their role in explaining molecular properties like paramagnetism in oxygen.

What is a key difference between molecular orbital theory and valence bond theory?

• Valence bond theory considers electrons delocalized throughout the molecule.

• Molecular orbital theory considers electrons delocalized throughout the molecule.

• Valence bond theory predicts paramagnetism in oxygen.

• Molecular orbital theory considers electrons localized between atoms.

What results from the constructive interference of atomic orbital wave functions?

• A bonding molecular orbital

• A node between nuclei

• An antibonding molecular orbital

• A decrease in electron density

Which orbitals are involved in lateral overlap to form pi molecular orbitals?

• s orbitals

• d orbitals

• px orbitals

• py and pz orbitals

Which principle states that orbitals are filled from lower to higher energy?

• Hund's rule

• Pauli exclusion principle

• Aufbau principle

• Heisenberg uncertainty principle

What is the bond order of diatomic oxygen (O2) according to molecular orbital theory?

• 3

• 4

• 2

• 1

What causes the discrepancy in the order of molecular orbitals in homonuclear diatomic molecules?

• s-p mixing

• Electron spin

• Atomic size

• Bond length

In which molecules is s-p mixing negligible?

• Li2 and Be2

• O2 and F2

• B2 and C2

• N2 and O2

What happens to the sigma-s and sigma-p orbitals during s-p mixing?

• Sigma-s becomes more stable, sigma-p becomes less stable

• Both sigma-s and sigma-p become less stable

• Both sigma-s and sigma-p become more stable

• Sigma-s becomes less stable, sigma-p becomes more stable

Why does s-p mixing not affect bond order calculations?

• It only affects antibonding orbitals

• It rearranges the order of bonding orbitals

• It changes the number of electrons

• It affects only the energy levels

What is the effect of increasing effective nuclear charge on atomic radii?

• Atomic radii remain unchanged

• Atomic radii become irregular

• Atomic radii expand

• Atomic radii contract