A Level Chemistry OCR Practice Exam

What is heterolytic fission?

1. The breaking of a covalent bond with one electron going to each atom, forming two radicals.

2. The breaking of a covalent bond where both electrons go to one atom, forming a cation and an anion.

3. The cleavage of ionic bonds in an ionic compound.

4. A method of ionizing molecules for mass spectrometry.

The correct answer is: The breaking of a covalent bond where both electrons go to one atom, forming a cation and an anion.

Heterolytic fission refers to the process where a covalent bond is cleaved in such a way that both electrons from the bond are transferred to one of the atoms involved. This results in the formation of a cation (positively charged ion) and an anion (negatively charged ion). This is an important process in various chemical reactions, especially in mechanisms involving polar molecules. The unequal distribution of electrons leads to the generation of ions, which can play a crucial role in further chemical reactions and stabilize radical intermediates. The other options describe different processes: the first option mistakenly describes homolytic fission, where each atom retains one electron, forming radicals. The third option pertains to the cleavage of ionic bonds, which differs fundamentally from covalent bond breaking. The fourth option refers to a technique used in mass spectrometry rather than a bond-breaking process. Understanding heterolytic fission is crucial in the context of organic chemistry and reaction mechanisms, where knowing how bonds break and form can elucidate the behavior of molecules in various reactions.