Question

Why is it easier to remove an electron from a sodium atom than a magnesium atom

Answer 1

Electron removal is easier from a sodium atom than a magnesium atom because sodium's 3s electron has lower electrostatic attraction and less shielding compared to magnesium's 3s electrons, and subsequent ionization energies always increase.

Step-by-step explanation:

It is easier to remove an electron from a sodium atom than a magnesium atom due to differences in electron configuration and the resulting ionization energy. When comparing sodium and magnesium, both elements are in the same period with sodium having one less proton and one less electron. For magnesium, the first ionization energy involves removing an electron from a filled 3s subshell, whereas for sodium, the electron removed is a 3s electron, but for aluminum (Al), which follows magnesium in the periodic table, the electron being removed is from the 3p subshell. As there's only one electron in the 3p subshell for aluminum and it is shielded by both the filled 3s subshell and all inner core electrons, it is slightly easier to remove compared to magnesium's 3s electron. Furthermore, when considering successive ionization energies, the ionization energy increases as you remove more electrons chiefly due to increasing electrostatic attraction to the resulting cation.

Answer 2

It doesn't take much energy to remove one electron from a sodium atom to form an Na+ ion with a filled-shell electron configuration. The first ionization energy of magnesium is larger than sodium because magnesium has one more proton in its nucleus to hold on to the electrons in the 3s orbital.