What is the oxidation state of the ion most likely to arise from an atom with an electron configuration of 1s² 2s² 2p⁶ 3s²? A) Minus five, B) minus four, C) minus two, D) plus two, or E) plus four.
The electron configuration tells us the distribution of electrons in their ground state. The question tells us that this is the electron configuration of an atom. And atoms are neutral species. If we count up the electrons in our electron configuration, we’ll see that this has 12 electrons. And since we know this is the electron configuration for an atom which is neutral, it must also have 12 protons.
If we take a look at the periodic table, we’ll see that the element that has an atomic number of 12, and therefore 12 protons, is magnesium, which is in group two of the periodic table. In this question, we’re interested in the ion that’s most likely to arise from this element. Elements in group two of the periodic table are most likely to lose the two electrons in their outer shell, in this case, the 3s² orbital. This means that the ion that magnesium is most likely to form will be the magnesium two plus ion. We’re interested in the oxidation state of this ion.
The oxidation state of an ion is going to be equal to the charge of the ion. So, the oxidation state of the magnesium two plus ion will be plus two. This matches answer choice D.
So, the oxidation state of the ion that’s most likely to arise from the atom with the electron configuration 1s² 2s² 2p⁶ 3s² is plus two.