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What is Magnetic Moment (Spin-only)?
Magnetic moment spin only refers to the contribution from electron spin without orbital effects. It is estimated with the formula mu equals square root of n times n plus two in units of Bohr magnetons. Here n equals the number of unpaired electrons and relates to the spin quantum number S by n equals two S. This approximation is used for many transition metal complexes.
FAQs
How is the spin only magnetic moment calculated?
It uses μ = √(n(n+2)) in units of Bohr magnetons where n is the number of unpaired electrons. Equivalently using the spin quantum number S the value is μ = 2√(S(S+1)).
What is the relationship between S and n?
For spin only magnetism n = 2S. The spin multiplicity is 2S+1 which reflects the number of MS states accessible for the given spin configuration.
Why can experimental values be higher than the spin only estimate?
Orbital contributions spin orbit coupling and temperature dependent effects add to the spin component. Strongly distorted or heavy atom complexes often show values exceeding the simple spin only prediction.
What units are displayed?
Results are shown in μB and converted to SI units J·T-1 using the Bohr magneton constant. This lets you compare with magnetic moments reported in different unit systems.
Can I compare a measured value with the estimate?
Yes. Enter an experimental μ in μB and the calculator will report the percent difference versus the spin only result to highlight agreement or deviations.
Does the method apply to all elements?
It best fits many first row transition metal ions with weak to moderate ligand fields. For lanthanides actinides and strong crystal field or low symmetry cases orbital effects make the estimate less accurate.