Question

Why is th ionization energy of sodium less than that of magnesium

Answer 1

Answer:

Magnesium atom has a smaller radius and higher nuclear charge than a sodium atom, thus more energy will be required to remove the electron from the same orbital (3s), making the first ionisation energy of magnesium higher than that of sodium.

Second ionization energy of sodium greater than magnesium:

So after it losing its one electron it becomes more stable by attaining noble gas configuration and hence more enthalpy is required to remove an electron from the stable atom hence the second ionisation enthalpy of sodium is greater than that of Magnesium.

Answer 2

Answer:

ionization energy of sodium is less than magnesiun because in increasing of groups the atomic radii increases and nuclear force of attraction decreases