Consider the elements Mg, Al, S, P and Si, the correct increasing order of their first ionization enthalpy is :
Solution
<p>On moving left to right in a period of the periodic table,
Ionisation energy (I.E.) increases due to increase in effective nuclear
charge i.e. Z<sub>eff</sub>.</p>
<p>But due to extra stability of fully filled and half-filled electronic
configuration of Mg and P required ionisation enthalpy is more from
neighbouring elements.</p>
<p>i.e. First ionisation enthalpy order is Al < Mg < Si < S < P.</p>
About this question
Subject: Chemistry · Chapter: Periodic Table and Periodicity · Topic: Periodic Trends
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