A Level Chemistry OCR Practice Exam

Which statement accurately describes a pi-bond (π-bond)?

1. A bond formed by end-to-end overlap of s-orbitals

2. The reactive part of a triple bond only

3. A bond formed by sideways overlap of p-orbitals

4. A bond that does not affect molecule reactivity

The correct answer is: A bond formed by sideways overlap of p-orbitals

A pi-bond is formed by the sideways overlap of p-orbitals. In the context of molecular bonding, this type of bond occurs after a sigma bond has been established between two atoms, resulting in a double bond or a part of a triple bond. The p-orbitals engage in a side-to-side overlap, creating a bond above and below the plane of the nuclei of the bonding atoms, which contributes to the overall electron density around the bond. This formation gives pi-bonds distinct characteristics that influence the chemical behavior of molecules, particularly in terms of reactivity. For example, the presence of a pi-bond can make a molecule more reactive in certain types of reactions, such as addition reactions to alkenes and alkynes. Therefore, the description of a pi-bond as formed through sideways overlap of p-orbitals is accurate and fundamental to understanding its role in chemistry. The other options do not correctly characterize a pi-bond. While the first option incorrectly describes the bond formation method focusing on s-orbitals, the second option inaccurately limits the definition to just the reactive part of a triple bond, overlooking the role pi-bonds play in double bonds as well. The last option mistakenly claims that pi-bonds do