question_answer 99)

    Discuss the factors affecting electron gain enthalpy and trend in its variation in the periodic table.

Answer:

  Factors affecting electron gain enthalpy The magnitude of electron gain enthalpy depends on a number of factors such as: (i) Size of the atom: Smaller the size of the atom, stronger is the attraction for the added electron towards nucleus. Thus, smaller the size of atom, greater is the electron gain enthalpy. (ii) Nuclear charge: Greater the nuclear charge, Stronger is the attraction for the added electron towards nucleus. Thus, electron gain enthalpy increases as nuclear charge increases. (iii) Electronic configuration: The elements having stable configuration (half filled or fully filled valence subshells) have very little or no tendency to accept additional electron; hence, electron gain enthalpies are low or zero in these cases. Variation of electron gain enthalpies in periodic table: In general, the electron gain enthalpy becomes less negative in going from top to bottom in a group and more negative inning from left to right in a period.  However, electron gain enthalpy does not show a regular trend along a period or a group.