The spin-only magnetic moment of the Fe3+ ion is determined by its electronic configuration and the number of unpaired electrons. Electronic Configuration: The neutral iron atom ( ‌26‌Fe ) has the electronic configuration: [Ar]3d64s2 When it forms a Fe ‌3+ ion, it loses three electrons. The configuration becomes: [Ar]3d5 Number of Unpaired Electrons: In the Fe3+ ion, there are 5 electrons in the 3d subshell. All these electrons are unpaired, hence: n=5 Calculating the Spin-Only Magnetic Moment: The formula for the spin-only magnetic moment (µs) is: µs=√n(n+2)‌BM Substituting n=5 into the formula: µs=√5(5+2)=√35 Calculating further gives: µs≈5.85‌BM Therefore, the spin-only magnetic moment of Fe3+ is approximately 5.85 Bohr Magnetons (BM), which can be rounded to about 6 BM .