Valence Bond Theory and Molecular Orbitals

These flashcards cover essential concepts related to Valence Bond Theory, hybridization, and molecular orbital theory as discussed in the lecture notes.

What does Valence Bond Theory describe?

It describes the formation of bonds between atoms in molecules, focusing on the overlap of atomic orbitals.

What is hybridization in the context of atomic orbitals?

Hybridization is the mathematical combination of atomic orbitals to form new hybrid orbitals with geometric properties.

How does Valence Bond Theory explain the tetrahedral structure of methane (CH₄)?

It assumes promotion of an electron from the 2s level to the 2p level, leading to four unpaired electrons that hybridize to form four sp³ orbitals.

What are the bond angles expected in a tetrahedral structure?

The bond angles in a tetrahedral structure are approximately 109.5°.

What is the significance of the node in hybrid orbitals?

The node is a region where the probability of finding an electron is zero, indicating a change in phase of the orbital.

Why is hybridization considered a model rather than a physically observable phenomenon?

Hybridization is a mathematical operation that predicts molecular geometry but does not reflect physical reality.

What molecular shape do three equivalent sp² hybrid orbitals form?

They form a trigonal planar arrangement with bond angles of 120°.

In molecular orbital theory, what happens to atomic orbitals when they combine?

They interfere either constructively (adding electron density) to form bonding orbitals or destructively (subtracting electron density) to form antibonding orbitals.

What is the bond order in a molecular orbital diagram?

Bond order is calculated as the difference between the number of electrons in bonding and antibonding orbitals, divided by two.

How does bond length relate to bond order?

Generally, as bond order increases, bond length decreases due to increasing electron density between the bonded atoms.