Chemistry · Classification of Elements and Periodicity in Properties

The first ionization enthalpy (\( \Delta_iH \)) values of third period elements Na, Mg and Si are respectively 496, 737 and \( 786 \text{ kJ mol}^{-1} \). Predict whether the first \( \Delta_iH \) value for Al will be more close to \( 575 \text{ kJ mol}^{-1} \) or \( 760 \text{ kJ mol}^{-1} \).

1. A
   810 kJ mol⁻¹
2. B
   760 kJ mol⁻¹
3. C
   680 kJ mol⁻¹
4. D
   575 kJ mol⁻¹