A Level Chemistry OCR Practice Exam

What is the correct definition of second ionization energy?

1. The energy needed to remove an electron from a neutral atom

2. The energy to remove one electron from a mole of 2+ gaseous ions

3. The energy required to remove an electron from a mole of gaseous 1+ ions

4. The energy to remove several electrons in one step

The correct answer is: The energy required to remove an electron from a mole of gaseous 1+ ions

The definition of second ionization energy specifically refers to the energy required to remove an electron from a mole of gaseous 1+ ions, transforming them into gaseous 2+ ions. This process denotes the removal of an additional electron from an already ionized atom, which means the atom is now positively charged. In this context, the key aspect is that the starting point is the 1+ ion state, not a neutral atom or another ion state. The energy involved in this process is typically greater than that of the first ionization energy due to increased electrostatic attraction; the remaining electrons experience a stronger attraction from the positively charged nucleus after one electron has been removed. Other options reference either the removal of electrons from neutral atoms or involve incorrect states of the ions. This highlights the importance of recognizing the specific charge state of ions when discussing ionization energies.