Question 1

What is a successive ionisation enthalpy?

Accepted Answer

It is the energy needed to remove one electron from an isolated gaseous atom or ion. The first value refers to neutral Na, Mg or Al, while the next value refers to the ion produced by the previous removal.

Question 2

Why does every successive ionisation enthalpy increase?

Accepted Answer

After each electron is removed, the remaining electrons experience a greater effective nuclear attraction as the positive charge rises and the ion contracts. Removing an electron always requires energy, so successive ionisation enthalpies increase.

Question 3

Why is there a large jump in the ionisation enthalpies of Na, Mg and Al?

Accepted Answer

Their outer valence electrons are relatively easy to remove. Once these electrons are gone, the next electron must come from the stable Ne-like core, which is held much more strongly and therefore requires much more energy.

Question 4

How does the jump position reveal the number of valence electrons?

Accepted Answer

For Na, the jump follows the first removal because it has one valence electron. For Mg it follows the second removal, and for Al it follows the third, directly matching their 2,8,1, 2,8,2 and 2,8,3 configurations.

Question 5

What happens to the ion size after successive electron removal?

Accepted Answer

The ion becomes more positively charged and smaller relative to the preceding species. This contraction is a qualitative trend in the model rather than a fixed-size calibration.

Successive Ionisation Enthalpies — Peel the Atom Layer by Layer

About this lab

Practice