Resonance in Chemical Bonding

Nuclear magnetic resonance is based on many nuclei having spun, and all nuclei are electrically charged. When an external magnetic field is applied, energy can be transferred to a higher energy level from the base energy.

What are Resonance Structures?

The Lewis structure sets that describe the electron’s delocalisation in a molecule or a polyatomic ion are known as resonance structures.

Chemical bonding can be described using resonance structures in such circumstances.

Characteristics of Resonance

• It doesn’t exist in the actual world.
• The bond length in identical resonating structures is the same.
• The resonance hybrid has the least amount of energy hence most stability.
• The more resonance and resonance energy there is, the more stable the structure becomes.
• Resonance is a theoretical idea that has yet to be proven experimentally.

Rules for Delocalization and Resonance Structures

• Resonance structures should contain the same number of electrons; no electrons should be added or subtracted. (Count the number of electrons to see how many there are.)
• Each resonance structure follows the Lewis Structures writing rules.
• The structure’s hybridisation must remain constant.
• The structure’s skeleton cannot be altered (only the electrons move).
• The number of lone pairs in a resonance structure must be the same.

Identifying Viable Resonance Structures Using Formal Charges

While every resonance structure adds to the molecule’s entire electronic structure, their contributions may not be equal. One way of determining the viability of a resonance structure and its relative significance among other structures is to assign formal charges to atoms in molecules. 

Use the following formula to find the standard charge on a particular atom in a covalent species:

Formal Charge = (number of valence electrons in the free orbital)−(number of lone-pair electrons) − ½ (number bond pair electrons)

Rules for Estimating Resonant Structure Stability

• The more covalent bonds there are, the more stable the system is since more atoms will have complete octets.
• The structure with the fewest formal charges is more stable.
• The structure with the least formal charge separation is the most stable.
• Positive charges on the most electropositive (least electronegative) atom are more durable.
• Equivalent resonance forms have the same level of stability and contribute equally (e.g., benzene)

Bond Nature and Stability (Resonance)

How does the nature of a bond affect the stability of a molecule? 

The answer is resonance.

Resonance involves the breakage of old bonds and the formation of new bonds between atoms. The structures formed due to resonance always exist simultaneously in every specimen of the compound and contribute to the properties exhibited.