A Level Chemistry OCR Practice Exam

What symbol is used in reaction mechanisms to indicate the movement of an electron pair during covalent bond formation or breaking?

1. Curly arrow

2. Dotted arrow

3. Solid arrow

4. Dashed line

The correct answer is: Curly arrow

The curly arrow is the correct symbol used in reaction mechanisms to indicate the movement of an electron pair, especially during the processes of covalent bond formation or cleavage. This symbol visually represents the flow of electrons from one atom to another, highlighting the transfer of electron density and the changes that occur during a chemical reaction. In the context of organic chemistry and reaction mechanisms, a curly arrow starts from a lone pair of electrons or a bond and points to the atom or bond that is gaining the electrons. This notation is essential for understanding how reactions proceed at a molecular level, as it clarifies the electron movements that contribute to the formation and breaking of bonds. Understanding the curly arrow convention helps chemists predict the products of reactions and illustrates the underlying principles of electron sharing and transfer that are fundamental to covalent bonding. This notation ultimately aids in visualizing the electronic changes that accompany many chemical processes, making it a vital tool in studying reaction mechanisms.