Magnetic Properties of Transition Metals
Unpaired d electrons give paramagnetism with spin-only moment determined by their number.
Unpaired d electrons give paramagnetism with spin-only moment determined by their number.
The magnetism of a transition metal compound arises from unpaired electrons in its d orbitals. Compounds with unpaired electrons are paramagnetic and are attracted into a magnetic field. The spin-only magnetic moment is mu = sqrt(n(n+2)) Bohr magnetons, where n is the number of unpaired electrons. Ferromagnetism, as seen in iron, cobalt and nickel, arises when neighbouring spins align through exchange interactions and form domains. Magnetic measurements therefore help chemists determine the electron configuration of a complex.
Key ideas: Spin-only moment: mu = square root of n(n+2) Bohr magnetons, n unpaired electrons. Examples: Fe3+ high spin d5 gives 5.92 BM, Cu2+ gives 1.73, Mn2+ 5.92, Ni2+ 2.83, Zn2+ zero. Unpaired electrons give paramagnetism, all paired gives diamagnetism. Ferromagnetism in Fe, Co, Ni arises from aligned domains. Strong field ligands (CN-) can pair electrons giving low spin and fewer unpaired electrons.
Common mistakes and connections: Students count unpaired electrons using the free atom instead of the ion, or ignore ligand field strength: Fe(CN)6 3- has 1 unpaired electron but FeF6 3- has 5. Orbital contribution adds to observed moments, mostly for heavier metals. Links to crystal field splitting, high and low spin and electron configurations.
Spin-only magnetic moments, mu = sqrt(n(n+2)), for high-spin ions; Mn2+ with five unpaired d electrons reaches 5.92 BM. The interactive lesson shows this as a live animation or chart.
Mn2+ has five unpaired d electrons, giving a spin-only moment of about 5.92 Bohr magnetons.
Unpaired d electrons give paramagnetism with spin-only moment determined by their number.
Magnetic Properties of Transition Metals is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Inorganic Chemistry first: Variable Oxidation States, Colored Ions, Catalytic Behavior of Transition Metals.
The next topics in Inorganic Chemistry are Iron Chemistry and Blast Furnace.
Yes. The interactive lesson includes a self-check question on Magnetic Properties of Transition Metals, and the Inorganic Chemistry quiz draws on every topic in this area.
Magnetic Properties of Transition Metals is topic 58 of 113 in Inorganic Chemistry.