What oxidation states does neodymium exhibit?

Neodymium predominantly shows the +3 oxidation state in all ordinary compounds. The +2 state has been observed in solid-state halides (NdI2) and in some organometallic complexes under non-aqueous conditions. The +4 state is extremely rare — reported only in a few fluoride matrices at low temperatures — because ionizing the 4f electrons of Nd beyond +3 is energetically very unfavorable.

Why is +3 the dominant oxidation state for neodymium?

Neodymium's ground-state configuration is [Xe] 4f4 6s2 with one 5d electron in some excited states. Losing the two 6s and one effective outer electron (from 5d or 4f) costs three ionization energies that are more than recovered by lattice and hydration energies in Nd3+ compounds. The 4f4 configuration in Nd3+ is also somewhat stabilized by half-shell effects. Going to Nd4+ would require pulling a 4f electron from an inner subshell — the energy cost is prohibitive.

What is neodymium's electron configuration?

Ground state: [Xe] 4f4 6s2 (full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f4 5d0 6s2). When ionized to Nd3+, it loses the two 6s electrons and one 4f electron, giving [Xe] 4f3, identical to the Pr3+ ion configuration. The 4f electrons in Nd3+ are core-like and shielded, which is why they confer the element's characteristic optical and magnetic properties.

What is neodymium used for?

The largest use of neodymium is in neodymium-iron-boron (NdFeB) permanent magnets, which are the strongest permanent magnets known. They are found in hard disk drives, electric vehicle motors, wind turbine generators, and MRI machines. Neodymium is also used in Nd:YAG lasers, in didymium glass for glassblower and welder eye protection, and as a colorant in glass and ceramics (giving a violet-purple tint).

How does neodymium compare to other lanthanides in oxidation state behavior?

Most lanthanides are exclusively +3. Neodymium fits this norm, showing only trace +2 and +4 chemistry under special conditions. Exceptions in the series include cerium (stable +4 from [Xe] configuration), europium and samarium (stable +2 from half-filled or filled 4f configurations), and terbium (accessible +4). Neodymium's 4f4 configuration in the +3 state provides no special half-shell or full-shell driving force for alternative states.

Is neodymium toxic or radioactive?

Neodymium is not radioactive (its natural isotopes are stable or have very long half-lives) and is considered only mildly toxic in bulk form. The fine powder of NdFeB magnets can be a fire hazard and skin irritant. Nd3+ ions have been studied for effects on calcium ion channels, so direct biological exposure should be minimized, but the element is not classified as highly hazardous under ordinary industrial handling.

Neodymium Oxidation States

Name: Neodymium Oxidation States
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Author: Nham Vu

Interactive reference for neodymium oxidation states: Nd is almost exclusively +3, with its electron configuration, ionization energies, and key compounds including the NdFeB magnet alloy explained.

Atomic # 60 Nd Neodymium

Atomic Mass

144.242 u

Group

Lanthanides (f-block)

Period

Block

f-block

Electronegativity

1.14 (Pauling)

Oxidation States

+3 (dominant)

Neodymium exhibits one dominant oxidation state: +3. Its ground-state configuration is [Xe] 4f⁴ 6s². Losing two 6s electrons and one outer electron exposes a [Xe] 4f³ core for Nd³⁺, the thermodynamically stable form in all ordinary compounds. The +2 state appears in specialized solid-state halides and organometallic systems; +4 is limited to a handful of fluoride matrices at cryogenic temperatures.

Oxidation State	Stability	Notes
+3	Stable	Universal state in all aqueous and most solid-state chemistry. Nd³⁺ has configuration [Xe] 4f³. All common compounds (Nd₂O₃, NdCl₃, Nd₂(SO₄)₃) feature this state.
0	Elemental only	Assigned to pure neodymium metal by convention. Nd metal is a silvery, soft, reactive rare-earth solid.
+2	Rare / non-aqueous	Observed in NdI₂ and in some organometallic complexes. Not stable in water — Nd²⁺ instantly oxidizes to Nd³⁺ in aqueous solution. 4f⁴ configuration.
+4	Extremely rare	Only reported in fluoride matrices (e.g., Cs₂NdF₆) at low temperature. No stable +4 compounds under ordinary conditions. 4f² configuration. The high 4th ionization energy (estimated >3000 kJ/mol) makes it inaccessible in solution.

Ionization Energies
IE₁ = 533.1 kJ/mol | IE₂ = 1040 kJ/mol | IE₃ = 2130 kJ/mol | IE₄ ≈ 3900 kJ/mol (estimated)
The large jump from IE₃ to IE₄ reflects the cost of pulling a 4f electron from the shielded inner shell — this energy is not recovered by compound formation, so +3 is the practical ceiling in ordinary chemistry.

All commercially important and most laboratory neodymium compounds feature Nd in the +3 oxidation state. Nd³⁺ is a large ion (radius ~0.983 Å for 6-coordinate) with high coordination numbers (often 8–9) and high affinity for oxygen donors. Its characteristic absorption bands in the visible range give neodymium compounds a distinctive rose-violet color.

Compound	Formula	Nd State	Notes
Neodymium Oxide	Nd₂O₃	+3	Light blue-gray powder; main ore-processing product; used as a glass colorant and as a precursor to other Nd compounds.
Neodymium Chloride	NdCl₃	+3	Pink crystalline solid; soluble in water; common starting material for synthesis and organometallic chemistry.
Neodymium Fluoride	NdF₃	+3	Used in the production of Nd metal and in optical coatings; lower solubility than the chloride.
Neodymium Sulfate	Nd₂(SO₄)₃	+3	Pink crystalline salt; used in analytical chemistry and as a source of Nd3+ ions in solution studies.
Neodymium Nitrate	Nd(NO₃)₃	+3	Highly soluble pink salt; used in separation chemistry via solvent extraction processes.
Neodymium Carbonate	Nd₂(CO₃)₃	+3	Precipitated from solution; intermediate in rare-earth extraction and refining.
Neodymium Hydroxide	Nd(OH)₃	+3	Precipitates from alkaline Nd3+ solutions; insoluble, used as a refining intermediate.
Neodymium Bromide	NdBr₃	+3	Pink solid; precursor in organometallic synthesis and metallothermic reductions.
Neodymium Iodide (+2)	NdI₂	+2	Dark-colored solid; rare +2 state; formed by reduction of NdI₃ with Nd metal at high temperature.
NdFeB Alloy (Nd₂Fe₁₄B)	Nd₂Fe₁₄B	+3*	The basis of the strongest permanent magnets. Nd3+ ions reside on specific crystallographic sites contributing to the large magnetocrystalline anisotropy. (*Oxidation state is formal; the compound is metallic.)
Nd:YAG (Nd³⁺ in Y₃Al₅O₁₂)	Nd:Y₃Al₅O₁₂	+3	Laser gain medium. Nd3+ substitutes for Y3+ in the garnet host lattice; emits at 1064 nm (near-IR).
Neodymium Acetate	Nd(CH₃COO)₃	+3	Soluble carboxylate salt; used in sol-gel processes and as a precursor for Nd-doped thin films.

Ground State Configuration

Core [Xe]

+47

Xe core — 5 filled shells (1s through 5p)

Valence inner shell — 4 of 14 f-orbitals filled in Nd

Usually empty in ground state; used in bonding for some lanthanides

Outermost — lost on first and second ionization

Notation

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁴ 6s²

Noble gas: [Xe] 4f⁴ 6s²

Nd³⁺ ion: [Xe] 4f³

Nd²⁺ ion: [Xe] 4f⁴

Ionization Steps

[Xe] 4f⁴ 6s²

Neutral atom — 2 outer + 4 inner f-electrons

Nd⁺

[Xe] 4f⁴ 6s¹

Remove one 6s electron (IE₁ 533.1 kJ/mol)

Nd²⁺

[Xe] 4f⁴

Remove second 6s electron (IE₂ 1040 kJ/mol) → Nd2+ (NdI₂)

Nd³⁺

[Xe] 4f³

Remove one 4f electron (IE₃ 2130 kJ/mol) — dominant stable ion in all ordinary compounds

Nd⁴⁺

[Xe] 4f²

Remove second 4f electron (IE₄ ≈ 3900 kJ/mol) — not accessible in aqueous chemistry; only fluoride matrices at cryo-temperatures

Why are lanthanide 4f electrons so inner-shell? The 4f orbitals contract in energy and radial extent across the lanthanide series (lanthanide contraction). In neodymium, the 4f electrons are shielded by the outer 5s and 5p shells and do not participate in chemical bonding — they behave as core electrons. This is why Nd³⁺ with its 4f³ configuration retains strong magnetic moments (3 unpaired f-electrons) while being chemically unreactive toward oxidation state changes.

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Summary

Interactive reference for neodymium oxidation states: Nd is almost exclusively +3, with its electron configuration, ionization energies, and key compounds including the NdFeB magnet alloy explained.

How it works

Click a tab — Oxidation States, Compounds, Electron Config, or Physical Props — to explore each area.
The Oxidation States panel explains why +3 dominates, with a table of all observed states and stability notes.
The Compounds panel lists common neodymium compounds with their formulas, oxidation state, and application notes.
The Electron Config panel shows the orbital filling diagram and the ionization energy steps to Nd3+.
The Physical Props panel provides atomic and material data for quick reference.
Click any monospace table cell to copy its value to the clipboard.

Use cases

Students studying lanthanide chemistry and the dominance of the +3 state across the f-block.
Chemistry teachers preparing lessons on rare-earth elements and oxidation state trends.
Materials scientists and engineers working with NdFeB permanent magnets.
Researchers assigning oxidation states in neodymium coordination compounds.
Anyone preparing for exams covering Period 6 or the lanthanide series.
Professionals in the rare-earth industry tracking neodymium compound chemistry.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu