Paramagnetism vs. diamagnetism compares two magnetic behaviors in Inorganic Chemistry II. Paramagnetic species have unpaired electrons and are attracted to a magnetic field, while diamagnetic species have all electrons paired and are weakly repelled.
Paramagnetism vs. diamagnetism is the basic magnetic comparison you use in Inorganic Chemistry II when a compound has to be classified by its electron arrangement. A species is paramagnetic if it has one or more unpaired electrons, and diamagnetic if all of its electrons are paired.
The reason this matters is that electrons behave like tiny magnets. When a magnetic field is applied, unpaired electrons can align more easily with that field, so paramagnetic substances are attracted. Paired electrons have opposite spins that cancel each other, so the net magnetic effect is much smaller and usually weakly repelled.
For transition metal complexes, you do not usually guess magnetism from the metal name alone. You first figure out the d electron count, then decide how those electrons fill the split d orbitals. If the complex is high-spin, it keeps more unpaired electrons and tends to be more strongly paramagnetic. If it is low-spin, more electrons pair up first, which can reduce or eliminate paramagnetism.
Ligands matter because they change the size of the splitting between d orbitals. Strong-field ligands often create larger splitting, which can push electrons to pair in the lower orbitals rather than occupy higher ones. That is why the same metal ion can switch from paramagnetic to diamagnetic depending on the ligand set and geometry.
A useful way to think about the distinction is this: magnetism is not the whole story, it is the visible outcome of the electron configuration. If you can count unpaired electrons, you can usually predict whether a coordination complex will be attracted to a magnetic field or only show the small background diamagnetism that nearly all substances have.
This term shows up everywhere in the coordination chemistry part of Inorganic Chemistry II because magnetism is one of the quickest checks on a complex’s electron arrangement. If you know whether a complex is para- or diamagnetic, you can often narrow down its spin state, ligand field strength, and even whether a proposed structure makes sense.
It also connects directly to high-spin and low-spin complexes. A classic classroom move is to compare two octahedral complexes with the same metal ion but different ligands, then explain why one has unpaired electrons and the other does not. That lets you connect electron counting to real measurements instead of treating orbital filling like a memorization exercise.
You will also see this idea in lab-style questions where a complex’s magnetic behavior is used as evidence. If a sample is attracted to a magnetic field, that tells you there are unpaired electrons somewhere in the electronic structure. If it is diamagnetic, you know all the electrons are paired, which immediately rules out certain configurations.
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Visual cheatsheet
view galleryUnpaired Electrons
This is the direct reason a species becomes paramagnetic. When you count unpaired electrons in a metal complex, you are really predicting whether there is a net magnetic moment left after electron pairing. More unpaired electrons usually means stronger paramagnetism, while zero unpaired electrons gives diamagnetism.
Spin State
Spin state tells you whether electrons stay separated in higher orbitals or pair up in lower ones. High-spin complexes usually keep more unpaired electrons, so they are often paramagnetic. Low-spin complexes pair electrons sooner, which can make them less magnetic or diamagnetic.
Ligand Field Theory
Ligand field theory explains why different ligands change the splitting of d orbitals. That splitting controls whether electrons are more likely to pair or remain unpaired. So magnetism becomes a measurable result of ligand strength and the orbital energy pattern around the metal.
Magnetic Susceptibility
Magnetic susceptibility is the property you measure when checking magnetic behavior. Paramagnetic compounds have positive susceptibility because they are attracted to a magnetic field, while diamagnetic compounds have small negative susceptibility. In problem sets, this is often the data point you use to infer electron pairing.
A quiz question might give you a transition metal complex and ask whether it is paramagnetic or diamagnetic. Your job is to count d electrons, fill the split orbitals using the ligand environment, and then identify the number of unpaired electrons. If the complex is high-spin, look for leftover unpaired electrons and say it is paramagnetic. If all electrons pair, call it diamagnetic.
You may also be asked to explain a magnetic measurement in a short answer or lab report. In that case, connect the observed attraction or weak repulsion to the electron configuration, not just the word itself. A good response names the spin state, the ligand field strength, and the final unpaired-electron count.
These are related but not the same thing. Paramagnetism and diamagnetism describe the magnetic behavior of a substance, while magnetic susceptibility is the measurement or sign you use to describe how strongly it responds to a magnetic field. In practice, susceptibility helps you tell which behavior a compound has.
Paramagnetism means a species has at least one unpaired electron, so it is attracted to an external magnetic field.
Diamagnetism means all electrons are paired, which gives a weak repulsion from a magnetic field.
In coordination chemistry, you usually predict magnetism by counting d electrons and checking how they fill split d orbitals.
High-spin complexes tend to be more paramagnetic because they keep more electrons unpaired.
Ligand strength can change the spin state, which is why the same metal ion can show different magnetic behavior in different complexes.
It is the comparison between compounds with unpaired electrons and compounds with all electrons paired. Paramagnetic species are attracted to a magnetic field, while diamagnetic species are weakly repelled. In Inorganic Chemistry II, this comes up most often when you predict the spin state of transition metal complexes.
Start by counting the metal’s d electrons, then place them into the split d orbitals created by the ligand field. If you end up with one or more unpaired electrons, the complex is paramagnetic. If every electron is paired, it is diamagnetic.
High-spin complexes keep electrons spread out instead of pairing them early, so more unpaired electrons remain. Those unpaired electrons create the magnetic response. Low-spin complexes pair electrons more often, which reduces paramagnetism.
No. Diamagnetism is a real magnetic response, but it is weak and opposite to the applied field. Nearly all substances show some diamagnetism, but it is usually overshadowed when a compound also has unpaired electrons and becomes paramagnetic.