Question

Which of the following has lowest ionisation enthalphy....... Na, K, Mg, Al

Answer 1

Answer:

Al has lowest ionisation enthalpy

Explanation:

$al =1s ^{2} 2s^{2} 2p^{6} 3s^{2} 3p ^{1} \\ k = 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{3} \\ na = 1s^{2} 2s^{2} 2p^{6} 3s^{1} \\ mg = 1s^{2} 2s^{2} 2p^{6} 3s^{2}$

Al and Na has 1 electron in outermost shell. It will be easier to remove 1 electron from aluminium.

it would be hard to remove Na electron as Half filled shells are more stable and Na outermost shell is half filled.