The first ionization enthalpy (IE) of the third-period elements Na, Mg, and Si are respectively 496, 737, and 786 kJ mol-1. Predict whether the first IE value of Al will be more close to 575 or 760 kJ mol-1 Justify your answer.
The first ionization enthalpy (IE) of Al will be more close to 575 kJ mol-1. The value of Al should be lower than that of Mg because of the effective shielding of 3p electrons from the nucleus by 3s electrons
