Element identity
Atomic number, symbol, relative atomic mass display and periodic position are established reference data.
Atomic / electronic model
Ground-state electron configuration and atomic reference values are compiled/evaluated data; orbital graphics are teaching probability models, not photographs.
Material / molecular structure
The displayed ordinary structure is based on established material or molecular science; simplified viewers are labelled as teaching schematics where exact crystallographic coordinates are not rendered.
Temperature / phase path
Transition values are reference/evaluated values for the stated teaching path; pressure, purity and allotropy can matter.
Geography
Real pins use reviewed place/dataset context. Conceptual layers are used when country pins would imply false occurrence, unsafe inventory or an incomplete global distribution.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Iron (Fe)
Explore iron as a transition metal whose partially filled 3d shell connects chemistry, magnetism and materials science: BCC and FCC crystal phases, the Curie transition, stable isotopes, ores, steelmaking, production geography and temperature-dependent structure.
Iron atomic number, mass, protons, electrons and electron configuration
Iron: quick answers
How many protons, neutrons and electrons does iron have?
Iron’s atomic number is 26, so every iron atom has 26 protons, and a neutral atom also has 26 electrons. Its most common natural isotope, iron-56, has 30 neutrons (other isotopes have different neutron counts).
What is the symbol for iron?
The chemical symbol for iron is Fe.
Is iron a solid, liquid or gas at room temperature?
Iron is a solid at room temperature (about 25 °C).
What family (group) is iron in?
Iron is a transition metal, in group 8, period 4 of the periodic table.
What is the electron configuration of iron?
The ground-state electron configuration of iron is [Ar] 3d⁶ 4s².
From atomic number to chemistry
Read these as a chain of causes, not as isolated facts. Each step links to the concept hub if you want the underlying idea explained.
Twenty-six protons define iron; neutral Fe contains 26 electrons.
A partially filled d subshell supports transition-metal chemistry and magnetic moments.
Multiple accessible oxidation states underpin corrosion, minerals and biological redox chemistry.
Iron changes magnetic order and crystal structure as temperature rises before melting.
Iron sits in the center of the Period 4 transition metals
Iron is a Group 8 d-block element between manganese and cobalt. Its partially filled 3d states support several oxidation states, magnetic behavior and extensive alloy chemistry.
Iron Visual Lab
Decode the Fe tile, rotate a ⁵⁶Fe educational nucleus, inspect the 2–8–14–2 shell model, compare representative 4s and 3d probability-cloud shapes, explore BCC/FCC crystal structure and connect iron to magnets, steel, biology and geology.
Seven facts packed into one square
Iron in one minute
[Ar] 3d⁶ 4s². Partially filled d states help explain transition-metal chemistry and magnetism.
⁵⁶Fe dominates nature. Four stable isotopes occur naturally.
Room-temperature α-Fe is BCC and ferromagnetic.
The Curie transition is magnetic, not a crystal change. BCC iron becomes paramagnetic before the later BCC→FCC transition.
Steel is an alloy family. Its properties depend on carbon and other alloying elements plus processing.
2 · 8 · 14 · 2 electrons by principal shell
Shell totals are useful for counting. The orbital/subshell description [Ar] 3d⁶ 4s² is needed for transition-metal chemistry.
Body-centred cubic (BCC)
At ordinary temperatures pure α-iron has a body-centred-cubic lattice. Below its Curie temperature this phase is also ferromagnetic.
Materials-science phase referenceBCC → FCC → BCC before melting
At approximately standard pressure, pure iron is BCC α-Fe at lower temperature, FCC γ-Fe at intermediate high temperature and BCC δ-Fe just below melting.
Why are 3d electrons important?
Partially occupied 3d-derived states contribute to iron’s magnetic moments, bonding and transition-metal chemistry. The cloud is a probability-density model, not a classical orbit.
Choose a card to connect atomic ideas to materials and Earth systems
Iron is the base element of the world’s dominant structural alloy family
Carbon and other alloying elements, heat treatment and phase transformations let engineers tune strength, hardness, ductility and corrosion behavior across many kinds of steel.
Iron magnetism: magnetic order changes before crystal structure does
Iron is an excellent example of why magnetic state and crystal phase must be described separately. At ordinary pressure, α-iron remains BCC through its Curie transition; the BCC→FCC structural change comes at a higher temperature.
Atomic moments begin with 3d electrons
Iron’s partially filled 3d-derived states support magnetic moments. In a solid these states interact collectively rather than behaving as isolated atoms.
Below the Curie temperature: ferromagnetic order
Below about 1043 K, domains can align so α-iron displays ferromagnetic behavior under suitable conditions.
Above Curie: BCC but paramagnetic
Thermal disorder destroys long-range ferromagnetic order, yet the crystal is still BCC α-Fe until the later α→γ transition.
Later: crystal structure changes
Near 1185 K the lattice becomes FCC γ-Fe, then near 1667 K returns to BCC δ-Fe before melting near 1811 K.
Iron physical, atomic, chemical and magnetic reference data
Iron needs several distinct scientific layers—atomic, physical, thermal, chemical, magnetic and isotopic—so they are kept separate instead of being flattened into one long table.
| Atomic number | 26 | NIST/RSC |
|---|---|---|
| Relative atomic mass | 55.845 | RSC/NIST |
| Electron configuration | [Ar] 3d⁶ 4s² | NIST |
| First ionization energy | ≈762.5 kJ/mol | NIST |
| Electronegativity | 1.83 | Pauling scale |
| Density near room temperature | ≈7.87 g/cm³ | RSC |
|---|---|---|
| Room-temperature crystal | BCC α-Fe | reference phase data |
| Appearance | lustrous metallic grey | RSC |
| State at 20 °C | solid | RSC |
| Curie temperature | ≈1043 K | magnetic transition |
|---|---|---|
| α→γ structure transition | ≈1185 K | BCC→FCC |
| γ→δ structure transition | ≈1667 K | FCC→BCC |
| Melting point | 1811 K | RSC |
| Boiling point | 3134 K | RSC |
| Common oxidation states | +2, +3 | common chemistry |
|---|---|---|
| Representative oxides | FeO, Fe₂O₃, Fe₃O₄ | multiple oxidation states |
| Corrosion | environment-dependent oxidation/hydroxide products | surface chemistry |
| Low-temperature ordinary phase | α-Fe · BCC · ferromagnetic below Curie | collective solid-state behavior |
|---|---|---|
| Above Curie, before α→γ | BCC α-Fe · paramagnetic | same crystal, different magnetic order |
| Magnetic model warning | not explained by isolated atoms alone | band/exchange physics |
| ⁵⁴Fe | 5.845% | stable |
|---|---|---|
| ⁵⁶Fe | 91.754% | stable |
| ⁵⁷Fe | 2.119% | stable |
| ⁵⁸Fe | 0.282% | stable |
Iron compared with manganese and cobalt
Neighboring transition metals show why d-block chemistry cannot be reduced to one smooth trend. Electron occupancy, magnetic order, oxidation states and crystal structures all matter.
| Configuration | [Ar] 3d⁵ 4s² |
|---|---|
| Context | many oxidation states |
| Configuration | [Ar] 3d⁶ 4s² |
|---|---|
| Context | BCC/FCC phases · ferromagnetism |
| Configuration | [Ar] 3d⁷ 4s² |
|---|---|
| Context | ferromagnetic metal |
Iron changes magnetic order, then crystal structure, before melting
Iron has multiple solid regions as temperature rises. The Curie marker is especially important because it changes magnetic order without changing the BCC lattice.
≈1043 KBCC→FCC
≈1185 KFCC→BCC
≈1667 Kmelt
1811 Kboil
3134 K3600 K
≈1043 K: ferromagnetic→paramagnetic while BCC remains BCC. ≈1185 K: BCC α-Fe→FCC γ-Fe. ≈1667 K: FCC γ-Fe→BCC δ-Fe. 1811 K: melting.
At 293 K: BCC α-iron, ferromagnetic region.Where on Earth is iron ore mined, and how is that different from iron’s natural abundance?
The map separates dated mine-production estimates from geological occurrence. Iron is abundant in Earth materials; production markers show economic activity, not the full natural distribution of iron.
From meteorites and bloomery iron to modern steel
Meteoric iron
Iron-nickel meteorites provided workable metallic iron before large-scale smelting technologies were developed.
Smelting expands
Improved furnaces and forging made terrestrial iron increasingly important for tools, weapons and structures.
From ferrum
The symbol Fe comes from the Latin word ferrum.
Steel becomes infrastructure
Control of carbon, alloying and heat treatment turned iron into a huge family of engineered steels.
How iron moves from geological ore to useful metal
Industrial routes vary and are highly engineered. This page keeps the process conceptual: concentrate iron-bearing minerals, chemically reduce iron oxides, refine composition and then cast/form the metal or steel.
Mine + beneficiate ore
Iron-bearing ores such as hematite and magnetite are mined and processed to raise iron content and control feed quality.
Prepare furnace or reduction feed
Ore fines may be agglomerated or pelletized depending on route; composition and size are controlled for stable processing.
Reduce iron oxides
Industrial reduction removes oxygen from iron oxides using carbon-based or alternative reducing systems depending on technology.
Refine, alloy and shape
Carbon and other elements are adjusted to make iron or steel grades, then material is cast and worked into useful products.
What is iron used for?
Structural steel
Buildings, bridges and infrastructure rely on iron-based steels whose composition and processing tune strength and toughness.
Transport
Vehicles, rails, ships and machinery use iron alloys for cost-effective structural performance.
Machines + tools
Steels and cast irons provide wear resistance, stiffness and machinability across engineering systems.
Magnetic systems
Iron-rich soft magnetic materials are central to motors, transformers and electromagnets.
Biology
Iron ions are essential in hemoglobin, electron-transfer proteins and many enzymes, though biological iron is tightly regulated.
Chemical industry
Iron compounds and iron-containing catalysts support pigments, water treatment and industrial chemistry.
Fe²⁺, Fe³⁺, oxides and corrosion products
Iron commonly accesses +2 and +3 oxidation states. Real minerals, rust layers and coordination compounds can contain mixtures of phases and oxidation states.
Iron(II)
Fe²⁺ appears in many salts, minerals and biological systems. Its chemistry depends strongly on ligands and redox conditions.
Iron(III)
Fe³⁺ is common in oxidizing environments and in iron(III) oxides/hydroxides.
Magnetite
Magnetite contains both Fe(II) and Fe(III) in an inverse-spinel structure and is strongly magnetic.
Iron-54, iron-56, iron-57 and iron-58
Natural iron contains four stable isotopes. The interactive isotope view connects iron’s fixed 26-proton identity to changing neutron count without reducing the topic to a static table.
26 protons · 30 neutrons · stable
Iron-56 dominates natural iron. Like every iron isotope it has 26 protons; its mass number 56 comes from 26 protons plus 30 neutrons.
Five-question Iron check
What is iron’s atomic number?
What changes at iron’s Curie temperature?
Which structure is γ-iron?
Which isotope dominates natural iron?
Why is “solid iron” not one crystal structure at all temperatures?
Iron questions: quick answer first, then the mechanism
The explanations deliberately separate atom-level electron configuration, collective magnetism, crystal structure, oxidation chemistry and steel alloy behavior.
Why is iron magnetic?
Short answer: Ordinary α-iron is ferromagnetic below its Curie temperature because exchange interactions favor long-range alignment of electronic magnetic moments into domains.
Unpaired d electrons are part of the story, but “unpaired electrons = ferromagnet” is incomplete. Ferromagnetism is a collective solid-state phenomenon: quantum-mechanical exchange interactions and the crystal/electronic structure allow many atomic moments to order cooperatively. Domains form, and an applied field can change their orientation and size.
Heating above the Curie temperature destroys long-range ferromagnetic order even though the atoms still possess electronic magnetic moments. Iron’s different crystal phases also have different magnetic behavior.
Key point: Iron magnetism is collective exchange-driven ordering in a solid, not merely the presence of individual unpaired electrons.
Why does iron change crystal structure before it melts?
Short answer: Different lattices have different free energies at different temperatures.
At approximately standard pressure, BCC α-Fe is stable at lower temperature, FCC γ-Fe becomes stable at higher temperature, and BCC δ-Fe reappears close to melting. These are solid-solid transitions.
Is the Curie temperature the same as the BCC-to-FCC transition?
Short answer: No.
Near 1043 K iron loses long-range ferromagnetic order but remains BCC α-Fe. The BCC→FCC α→γ structural transition occurs later, near 1185 K.
Why are Fe²⁺ and Fe³⁺ both common?
Short answer: Iron’s d-block electronic structure supports more than one accessible oxidation state.
Which state is stabilized depends on ligands, redox conditions, crystal environment and reaction context. Oxidation state is a bookkeeping framework rather than a literal localized charge picture.
What is the difference between iron and steel?
Short answer: Iron is the element; steel is an iron-based alloy family.
Steel contains controlled carbon and often other alloying elements. Processing and microstructure can change properties dramatically even though iron remains the dominant element.
Scientific sources for Iron
Core atomic, isotopic, phase and production statements are tied to authoritative or technical references. Year-dependent mine figures are explicitly labeled as estimates for that year.
Questions to ask next about Iron
A good element lesson should lead to the next useful question, not end after a list of facts.
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