Paramagnetism, Diamagnetism and Ferromagnetism: Difference Explained
Chemistry · D And F Block Elements · NEET
The difference is about electrons and how a magnet pulls the substance. Diamagnetic = all electrons paired, weakly pushed away by a magnet. Paramagnetic = has unpaired electrons, weakly pulled in. Ferromagnetic = many unpaired electron spins line up in the same direction, so it is very strongly pulled in (like iron). Memory hook: "Di = Denied (paired, pushed out), Para = Pulled in (unpaired), Ferro = Ferociously pulled (iron, super strong)."
Diamagnetic ions have all electrons paired and are weakly repelled; paramagnetic ions have unpaired electrons pointing randomly and are weakly attracted; ferromagnetic metals (Fe, Co, Ni) have their unpaired spins aligned in the same direction and are strongly attracted.
Your doubts, answered
How do I quickly tell if an ion is paramagnetic or diamagnetic?
Count the unpaired electrons. Write the electron configuration of the ion (for transition metals, remove the 4s electrons first, then the 3d). If even ONE d-electron is unpaired, the ion is paramagnetic (pulled in by a magnet). If every electron is paired (d0, d10, or a fully paired set), it is diamagnetic (weakly pushed away). Example: Sc3+ is 3d0 = diamagnetic. Cu2+ is 3d9 = one unpaired = paramagnetic.
Is ferromagnetism just a strong type of paramagnetism?
Yes, and NTA has tested this exact line. Ferromagnetism is called an extreme form of paramagnetism. Both need unpaired electrons. The difference: in a paramagnetic substance the tiny magnets (spins) point in random directions and only line up a little in an external field. In a ferromagnetic substance (like Fe, Co, Ni) the spins of neighbouring atoms lock together and all point the same way, giving a huge, permanent magnetisation. NEET 2025 called Statement 'Ferromagnetism is an extreme form of paramagnetism' TRUE.
Why is a diamagnetic substance pushed away by a magnet?
In a diamagnetic substance all electrons are paired, so their tiny magnetic effects cancel out. When you bring a magnet, the paired electrons set up a tiny opposing magnetic field (by Lenz's law type effect). This opposite field makes the substance get weakly repelled. It has NO permanent magnetism of its own.
What does the spin-only magnetic moment tell me?
The spin-only formula mu = square root of n(n+2) Bohr Magneton (BM) uses n = number of unpaired electrons. If n = 0, mu = 0, so the ion is diamagnetic. If n is more than 0, mu is more than 0, so the ion is paramagnetic. Bigger n means bigger mu and stronger paramagnetism. This is the number NEET makes you calculate.
Why is iron ferromagnetic but many other d-block ions are only paramagnetic?
Both iron and other transition metals have unpaired electrons. But ferromagnetism needs something extra: the unpaired spins of neighbouring atoms must be able to align together (couple) in domains. This special alignment happens only in a few metals like Fe, Co, Ni (and Gd). Most transition metal ions have unpaired electrons that stay random, so they are only weakly paramagnetic, not ferromagnetic.
⚠️ The NEET trap ✗ Thinking KMnO4 (MnO4^-) or K2Cr2O7 are paramagnetic because they are strongly coloured. ✓ Colour does NOT prove paramagnetism. MnO4^- has Mn in +7 (d0) and Cr2O7^2- has Cr in +6 (d0). With zero d-electrons they have zero unpaired electrons, so they are DIAMAGNETIC. Their colour comes from charge transfer, not from unpaired d-electrons. Only ions with unpaired d-electrons (like MnO4^2-, Mn is +6, d1) are paramagnetic. 🧠 No unpaired electron = no paramagnetism, no matter how bright the colour. Count electrons, do not trust the colour.
Real NEET questions
NEET 2025
Given below are two statements. Statement I: Ferromagnetism is considered as an extreme form of paramagnetism. Statement II: The number of unpaired electrons in a Cr2+ ion (Z = 24) is the same as that of a Nd3+ ion (Z = 60). In the light of the above statements, choose the correct answer.
A · Statement I is true but Statement II is false ✓
B · Statement I is false but Statement II is true
C · Both Statement I and Statement II are true
D · Both Statement I and Statement II are false
Solution: Statement I is TRUE: in a ferromagnetic solid the unpaired-electron spins of neighbouring atoms all align in the same direction, giving very strong magnetisation. This cooperative alignment is why we call ferromagnetism an extreme form of paramagnetism. Statement II is FALSE: Cr2+ is 3d4 = 4 unpaired electrons, but Nd3+ is [Xe]4f3 = 3 unpaired electrons. 4 is not the same as 3. So only Statement I is true.
NEET 2018
Which one of the following ions exhibits d-d transition and paramagnetism as well?
A · MnO4^-
B · Cr2O7^2-
C · CrO4^2-
D · MnO4^2- ✓
Solution: For a d-d transition AND paramagnetism you need at least one unpaired d-electron. In MnO4^- (Mn +7), Cr2O7^2- and CrO4^2- (Cr +6) the metal is d0, so they have no unpaired electron: they are diamagnetic and their colour is only from charge transfer. In MnO4^2- (manganate) Mn is +6 = d1, so it has one unpaired electron. It is paramagnetic and can show a real d-d transition. Answer: MnO4^2-.
NEET 2020
The calculated spin only magnetic moment of Cr2+ ion is:
A · 5.92 BM
B · 2.84 BM
C · 3.87 BM
D · 4.90 BM ✓
Solution: Cr2+ is [Ar]3d4, so it has n = 4 unpaired electrons. Because n is more than 0, Cr2+ is paramagnetic. Spin-only mu = square root of n(n+2) = square root of 4(4+2) = square root of 24 = 4.90 BM.
Solved D And F Block Elements NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
What is the main difference between paramagnetic and diamagnetic substances?
Paramagnetic substances have unpaired electrons and are weakly attracted (pulled in) by a magnet. Diamagnetic substances have all electrons paired and are weakly repelled (pushed away) by a magnet.
Which substances are ferromagnetic?
Only a few metals are ferromagnetic: iron (Fe), cobalt (Co), nickel (Ni), and gadolinium (Gd). In these, unpaired electron spins align together in domains, giving very strong, permanent magnetism.
How is ferromagnetism related to paramagnetism?
Ferromagnetism is an extreme (very strong) form of paramagnetism. Both need unpaired electrons, but in ferromagnetic solids the spins of neighbouring atoms all line up in the same direction instead of staying random. NEET 2025 marked this statement as true.
Can a coloured compound still be diamagnetic?
Yes. MnO4^- and Cr2O7^2- are brightly coloured but diamagnetic, because the metal is d0 (no unpaired electrons). Their colour comes from charge transfer, not unpaired d-electrons.
How do I count unpaired electrons for a transition metal ion?
First remove the 4s electrons, then the required number of 3d electrons to form the ion. Fill the remaining d-electrons using Hund's rule (singly first). The number left unpaired gives you n, which you put into mu = square root of n(n+2).
