Read the statement. Magnesium atoms have 12 electrons, with the configuration 2-8-2. If the first five ionization energies of magnesium are shown, which ionization energy would show a sudden sharp increase?

The electronic configuration of magnesium is:

1s² 2s² 2p⁶ 3s² = [Ne] 3s²

This means that for a magnesium atom, in order to have its outermost orbital full, the easiest way would be to lose the two outermost electrons. This is seen in its relatively low first two ionization energies. The third ionization energy is several times higher because the ion would move from a stable form to an highly unstable form. (Mg⁺² → Mg⁺³ + e⁻).

Sodium only has one electron in its outermost orbital, so its first ionization energy would be several times lower than the second.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.