Question

Sodium (Na), Magnesium (Mg), Aluminium (Al) and Silicon (Si) are arranged in the decreasing order of their atomic size. Which element has the highest ionization energy among them? Justify your answer scientifically.

Answer 1

Hint: The amount of energy required to remove the valence electron from an element is called ionization energy. The ionization increases from left to right and decreases from top to bottom in the periodic table. If we are going to remove the first electron then the ionization energy is called first ionization energy.

Complete step by step answer:
>The elements given in the question are Sodium (Na), Magnesium (Mg), Aluminium (Al) and Silicon (Si).
>We know that Sodium belongs to the IA group, Magnesium belongs to the IIA group, Aluminium belongs to the IIIA group and silicon belongs to the IVA group.
>All the given elements belong to different groups but they are present in the same period only.
>As we are moving from left to right in the periodic table electrons are going to be added to the same principal shell.
>We know that as per rules nuclear charge increases, from left to right in the periodic table because the added electrons shield each other poorly from the nucleus of the atom.
>As moving from left to right Effective nuclear charge increases, atomic radii decreases and ionization energy increases along the period.
>Therefore silicon is the element present at last in the same period among the given elements.
>So, silicon is the element with the highest ionization energy.

Note: Atomic size decreases as we are moving from left to right in the periodic table. As we are moving from left to right in the periodic table the coming electrons are going to add to the same principal shell. So, the nuclear attraction on the added electrons increases. Then ionization energy increases.