Spin-only magnetic moment
= Spin-only magnetic moment
{title2=$\mu_{\mathrm{eff}}$}
The <spin-only magnetic moment> neglects orbital contributions and approximates $g$ by two: $\mu_{\mathrm{eff}}=g\sqrt{S(S+1)}\mu_B=\sqrt{n(n+2)}\mu_B$ for $n$ parallel unpaired <electrons>. Four unpaired <electrons> give $\sqrt{24}\mu_B\simeq4.90\mu_B$.