A Level Chemistry OCR Practice Exam

What occurs during the second ionisation energy process?

1. One electron is removed from a neutral atom

2. One electron is removed from a gaseous 1+ ion

3. One electron is added to a gaseous atom

4. One electron is removed from a solid metal

The correct answer is: One electron is removed from a gaseous 1+ ion

During the second ionisation energy process, one electron is removed from a gaseous ion that already has a positive charge, specifically a 1+ ion. This process is characterized by the energy requirement to remove an additional electron after the first ionisation has already taken place, where the first electron was removed from a neutral atom, creating this 1+ ion. The ionisation energy reflects the energy changes involved in overcoming the attractive forces between the positive nucleus of the ion and the negatively charged electron being removed. Since the species undergoing the second ionisation energy has already lost an electron, it is crucial to specify that it is a gaseous ion, ensuring that the ionization process takes place in the gas phase where ionisation energies are typically measured accurately. This focus distinguishes the process from other states of matter, such as solids, where ionisation behavior can significantly differ due to the presence of lattice energies and other interactions. In contrast, removing an electron from a neutral atom or a solid metal does not pertain to the second ionisation process, and adding an electron does not involve ionisation but rather electron affinity. Thus, the emphasis on the gaseous 1+ ion in this choice correctly captures the essence of what happens during the second ionisation