Q. The energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state is called?
Answer: Ionization Potential
Notes: Ionization potential is the energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state. As we move down the group, ionization potential decreases. As we move across the period, ionization potential increases Electron affinity is the energy released on adding an electron to the outermost shell of an atom in its isolated gaseous state.