What is the electron configuration for the ion Al³⁺?

The correct electron configuration for the ion Al³⁺ is represented as [Ne]. To understand why this is the case, it’s important to start with the neutral aluminum atom, which has an atomic number of 13. This means a neutral aluminum atom has 13 electrons. The electron configuration for a neutral aluminum atom is 1s² 2s² 2p⁶ 3s² 3p¹ or, in shorthand notation, [Ne] 3s² 3p¹, where [Ne] represents the electron configuration of neon, which accounts for the first 10 electrons.

When aluminum loses three electrons to form Al³⁺, it does so primarily by removing the electrons from the outermost shell, which includes the 3s and 3p subshells. Specifically, the two electrons in the 3s subshell and one electron from the 3p subshell are removed. After this ionization, the resulting electron configuration reflects the full occupancy of the inner shells and only the core electrons are left, which corresponds to the configuration of neon, [Ne].

Thus, when considering Al³⁺, it has lost a total of three electrons, leading to the stable electron configuration of