Gallium commonly forms a $G^a$ ion. What is the electron configuration of $G^a$?

• A. $\left[Ne\right]s^2{p}^6{d}^{10}$
• B. $\left[Ar\right]d^{10}{s}^2{p}^1$
• C. $\left[Ar\right]d^8{s}^2$
• D. $\left[Ar\right]d^{10}$

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of gallium (Ga), which is 31, and write its ground-state electron configuration. Gallium's electron configuration is \([\mathrm{Ar}]\,3d^{10}\,4s^{2}\,4p^{1}\).
2. Understand that the \(\mathrm{Ga}^{3+}\) ion is formed by removing three electrons from the neutral gallium atom.
3. Recall the order in which electrons are removed when forming cations: electrons are first removed from the outermost shell (highest principal quantum number), which means removing electrons from the 4p and 4s orbitals before the 3d orbital.
4. Remove one electron from the 4p orbital and two electrons from the 4s orbital, since these are the highest energy electrons, to account for the +3 charge.
5. Write the resulting electron configuration after removing these three electrons, which will be \([\mathrm{Ar}]\,3d^{10}\).