Reaction mechanism is a stepwise description of each and every step involved in reaction so the correct option is A

Reaction Mechanism

The correct answer is option 'A', reaction mechanism. A reaction mechanism provides a detailed account of each step involved in a chemical reaction, including the movement of electrons, the energetics during bond cleavage and bond formation, and the rates of transformation of reactants into products. It explains how reactant molecules rearrange and bond with each other to form products.

Electron Movement

In a chemical reaction, electrons play a crucial role in the formation and breaking of chemical bonds. The movement of electrons determines the reactivity and stability of molecules. The reaction mechanism describes how electrons are transferred or shared between atoms during a reaction. It explains the movement of electrons from high energy orbitals to low energy orbitals, leading to the formation of new bonds and the breaking of existing bonds.

Energetics during Bond Cleavage and Bond Formation

During a chemical reaction, bonds between atoms are broken and new bonds are formed. The reaction mechanism explains the energy changes associated with these processes. Bond cleavage requires an input of energy, known as bond dissociation energy, as bonds are broken. This energy is absorbed from the surroundings. On the other hand, bond formation releases energy, known as bond formation energy, as new bonds are created. The reaction mechanism describes the energy changes during these processes and how they influence the overall energetics of the reaction.

Rates of Transformation (Kinetics)

The reaction mechanism also provides information about the rates of transformation of reactants into products. It describes the individual steps involved in the reaction and the order in which they occur. Each step in the mechanism has a specific rate constant associated with it, which determines how fast that step proceeds. The overall rate of the reaction is determined by the slowest step, known as the rate-determining step. The reaction mechanism helps to identify this step and understand the factors that control the reaction rate.

Conclusion

In summary, a reaction mechanism is a detailed account of the steps involved in a chemical reaction. It describes the movement of electrons, the energetics during bond cleavage and bond formation, and the rates of transformation of reactants into products. Understanding the reaction mechanism is crucial for predicting and controlling chemical reactions.