CBSE Class 10 Answered

The ionization enthalapy /ionization energy or E_I of an atom or molecule is the energy required to remove an electron from the isolated atom or ion. More generally, the nth ionization energy is the energy required to strip it of the nth electron after the first n − 1 electrons have been removed. It is considered a measure of the "reluctance" of an atom or ion to surrender an electron, or the "strength" by which the electron is bound; the greater the ionization energy, the more difficult it is to remove an electron.