Question

The first ionization potential of Mg, Al, P, and S follows the order:

• A. Mg < Al < P < S
• B. Al < Mg < P < S
• C. Al < Mg < S < P
• D. Mg < Al < S < P

Hint:

Look for exceptions in the period 3 ionization energy trend caused by stable electron configurations.

Answer 1

The Correct Option is C

Al's lone 3p1 electron, well shielded, has lowest IE. Mg's filled 3s2 subshell has moderate IE. P's half-filled 3p3 has highest IE (exchange stabilization). S's paired 3p4 has slightly lower IE than P.

\[\boxed{Al < Mg < S < P}\]