Question

The condition to be satisfied for the atomic orbitals to form molecule orbitals is (a) they must possess comparable energies (b) they must overlap to a considerable extent (c) they must be symmetrical with respect to the molecular axis (d) all the above

Short answer

The correct answer is (d) All the above.

Step-by-step solution

Analyze the Conditions

Analyze the options provided in the question one by one. Option (a) talks about comparable energies which is crucial for atomic orbitals to form molecular orbitals. Option (b) mentions substantial overlap which is another necessary condition for atomic orbitals to form molecular orbitals. Option (c) talks about symmetry with respect to the molecular axis which is again a fundamental requirement for atomic orbitals to form molecular orbitals.

Identify the Correct Answer

As each of these options is a condition that needs to be fulfilled for atomic orbitals to form molecular orbitals, the correct answer is that all these options (a, b, c) are necessary conditions. Hence, option (d) is the correct answer which says all the above options are correct.

Key concepts

Atomic Orbital Overlap

To discuss how atomic orbitals form molecular orbitals, let’s start with the concept of **atomic orbital overlap**. This is a critical factor when it comes to the formation of molecular orbitals. When two atoms come close to each other, their atomic orbitals can overlap. This overlap means the electron cloud of one atomic orbital starts to spread into the space occupied by another orbital. In essence:

• When atomic orbitals overlap significantly, a stable molecular orbital can be formed.
• The quality of this overlap influences the strength and type of the bond formed between the atoms.

Significant overlap helps in reducing the potential energy of the system, leading to the formation of a stable chemical bond. Poor overlap, on the other hand, leads to a weak interaction or no bonding at all. Think of it like a handshake; the firmer the handshake (overlap), the stronger the connection.

Symmetry in Molecular Orbitals

For atomic orbitals to effectively combine into molecular orbitals, they must possess the right kind of **symmetry**. Symmetry in molecular orbitals is an essential aspect to ensure proper orbital interaction. Here are a few key points:

• The symmetry of the orbitals relative to the molecular axis determines how they interact and overlap.
• If the orbitals are symmetrical with respect to each other, constructive interference can occur, enhancing the overlap.
• Non-symmetric orbitals may lead to destructive interference, reducing the potential for effective bonding.

To visualize it, imagine mirror images. For constructive interaction, both sides should align perfectly. This concept ensures the formation of bonding, anti-bonding, or even non-bonding molecular orbitals, depending on the type of symmetry present.

Comparable Energy Levels in Atomic Orbitals

The energy levels of atomic orbitals play a substantial role in determining whether they will combine into molecular orbitals. Only orbitals with **comparable energy levels** can effectively form molecular orbitals:

• If the energy levels are too different, the orbitals are unlikely to interact effectively.
• Relatively similar energy levels mean that the electrons can transition between the orbitals easily, facilitating bonding.
• Balance in energy ensures that neither orbital dominates, allowing for a stabilizing interaction.

Picture this like a dance; both partners need to move at the same pace (energy level) to create harmony. If their energies are compatible, they can form stable bonding interactions, creating a stable molecular structure.