Final answer:
The electron configuration of the Ga3+ ion is (Ar) 4s² 3d¹⁰, where gallium loses its outermost electrons, resulting in a pseudo noble gas configuration.
Step-by-step explanation:
The electron configuration of the Ga3+ ion is (Ar) 4s² 3d¹⁰. When gallium ionizes to form Ga3+, it loses the three electrons from the outermost orbitals. According to the principles of electron configuration, electrons are removed from the orbitals starting with the highest principal quantum number first. In the case of gallium, this means that the electron in the 4p orbital and the two electrons in the 4s orbital are removed, thus leaving behind a full 3d subshell. The resulting electron configuration of Ga3+ is a pseudo noble gas configuration with an argon core and a filled 3d subshell, which is chemically stable.