The following energies were found for an unknown element ionization. What is a common ion for the unknown element above?

Question

Serenity Allen · Accepted Answer

The expected charge is +3 (although +1 may exist as well).

This element, which has three valence electrons, is a member of the column headed by boron. How we know this is as follows: Suppose all of the first three ionization energies involved removal of valence electrons. If these electrons originate in the same subshell (2#p# for example) the ratio of these energies should be very close to a 1:2:3 ratio. Why? To understand, you must think about what is left over when an electron is removed. For example, when we remove the first electron, we are taking it out of an ion that has a charge of +1 (the nucleus and the remaining electrons). The electric force acting on the electron is proportional to the charge on the ion that is still present. The force acting on our electron and the energy required to remove it both increase with the charge on the rest of the atom. The second electron is removed from an ion with a charge of +2, and the third electron from an ion with a charge of +3. When we look at the element given, we find that #IE_2# and #IE_3# are very close to a 2:3 ratio, but #IE_1# does not fit the "pattern". It is lower than the 1:2:3 ratio would suggest. Why? Because it is not removed from the same subshell as electrons 2 and 3. It comes from a subshell having a higher energy (and therefore, requiring less added energy to remove). It tells us that the 1st electron is being removed from a subshell such as #2p#. Then, two electrons are taken from the same subshell (perhaps #2s#). The fourth electron requires a significantly higher amount of energy to remove, indicating that it is not a valence electron at all. Since three valence electrons are easily removed, our element with three of them should form an ion with a charge of +3.

Naomi Aronson · Answer

undefined The common ion for the unknown element is likely the one with the most stable electron configuration, which is typically the ionization energy with the highest value. Therefore, the common ion for the unknown element would be the ion with the highest ionization energy found in the given data.