Element 26 · Iron (Fe)
Iron Bohr model: diagram and electrons per shell
The iron Bohr model shows a iron atom (Fe) as a small nucleus with its electrons circling it in 4 shells: 2 in shell K, 8 in shell L, 14 in shell M and 2 in shell N. This page has a rotating 3D iron Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.
Rotate the iron Bohr model in 3D
Drag to orbit, scroll to zoom.
This is a Bohr model of iron (Fe), a simplified picture of a single iron atom. Its nucleus holds 26 protons, and a neutral iron atom has 26 electrons, arranged around it in 4 shells (2 in shell K, 8 in shell L, 14 in shell M and 2 in shell N).
Iron Bohr model diagram
Iron electrons per shell
A neutral iron atom has 26 electrons, one for each of its 26 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 14 in shell M and 2 in shell N.
| Shell | Shell number (n) | Electrons | Most it can hold (2n²) | Subshells |
|---|---|---|---|---|
| K | 1 | 2 | 2 | 1s2 |
| L | 2 | 8 | 8 | 2s2 2p6 |
| M | 3 | 14 | 18 | 3s2 3p6 3d6 |
| N | 4 | 2 | 32 | 4s2 |
How the iron Bohr model builds up, shell by shell
Watch the iron Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 14 in shell M and 2 in shell N) as it forms.
How to draw the iron Bohr model
- Find the atomic number. Iron has atomic number 26, so a neutral atom has 26 protons and 26 electrons.
- Draw the nucleus. Put a circle in the centre and write Fe in it. The 26 protons sit there with the neutrons.
- Draw the shells. Sketch 4 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
- Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 14 in shell M and 2 in shell N.
- Check the total. 2 + 8 + 14 + 2 = 26, the atomic number, so every electron is accounted for.
Atomic data for the iron Bohr model
The numbers behind the iron Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).
Identity
- Symbol
- Fe
- Atomic number
- 26
- Atomic mass
- 55.8452 u
- Family
- Transition Metals
- Position
- group 8, period 4
- Block
- d-block
Electron configuration
- Full
- 1s2 2s2 2p6 3s2 3p6 4s2 3d6
- Shorthand
- [Ar] 3d6 4s2
- Electrons per shell
- 2, 8, 14, 2
- Outer-shell electrons
- 2 in shell N
Ionisation energies
- I₁
- 762.5
- I₂
- 1561.9
- I₃
- 2957
- I₄
- 5290
- I₅
- 7240
- I₆
- 9560
- I₇
- 12060
- I₈
- 14580
Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.
Atomic radii
- Calculated (pm)
- 156
- Empirical (pm)
- 140
- Covalent (pm)
- 116
Electronegativity and electron affinity
- Electronegativity (Pauling)
- 1.83
- Electron affinity (kJ/mol)
- 14.785
Oxidation states
+2 +3
Charges the element commonly takes in compounds.
Physical properties, abundance and history of iron
Bulk properties of iron, how common it is, who discovered it and some of its compounds.
Physical properties
- Phase at room conditions
- Solid
- Appearance
- Lustrous metallic with a grayish tinge
- Melting point
- 1537.85°C (1811 K)
- Boiling point
- 2860.85°C (3134 K)
- Density
- 7.874 g/cm³
- Thermal conductivity (W/m·K)
- 80.4
- Specific heat (J/g·K)
- 0.449
- Molar heat capacity (J/mol·K)
- 25.1
- Heat of fusion (kJ/mol)
- 13.8
- Heat of vaporisation (kJ/mol)
- 340
Abundance
- Earth's crust (mg/kg)
- 56300
- Oceans (mg/L)
- 0.002
Discovery
- Year
- Ancient
Common compounds
- Ferrous Sulfate FeO4S
- Iron Fe
- Ferbam C9H18FeN3S6
- Iron chloride (FeCl3) Cl3Fe
- Ferric citrate C6H5FeO7
- Ferrous cation Fe+2
- Sodium Nitroprusside C5FeN6Na2O
- Sodium Feredetate C10H12FeN2NaO8
Compounds listed in the PubChem database.
Main isotopes of iron
Isotopes of iron share the same 26 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.
| Mass number | Natural abundance | Half-life | Decay |
|---|---|---|---|
| 54 | 5.845 % | stable | 2β⁺ |
| 55 | – | 2.756 y | EC |
| 56 | 91.754 % | stable | – |
| 57 | 2.119 % | stable | – |
| 58 | 0.282 % | stable | – |
| 60 | – | 2.62 My | β⁻ |
α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.
More about iron
- Iron on the periodic table – properties, isotopes, uses and the full iron page.
- Transition Metals – all transition metal elements and their trends.
- Bohr model of every element – the Bohr model of all 118 elements.