Iron
Silvery malleable and ductile metallic transition element. Has nine isotopes and is the fourth most abundant element in the earth's crust. Required by living organisms as a trace element (used in hemoglobin in humans.) Quite reactive, oxidizes in moist air, displaces hydrogen from dilute acids and combines with nonmetallic elements.
Gallery
Chemical ELements A Virtual Museum, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0> source: https://images-of-elements.com/iron.php
Emission spectrum
Physical Propertiesmass · density · phase · crystal
Atomic Mass
55.8450Da
Density
7.8700g/cm³
Phase (STP)
Solid
Melting Point
1811.2K
Boiling Point
3134.2K
Molar Heat
0.4490J/(mol·K)
Crystal Structure
BCC
Lattice Constant
2.870Å
Atomic Radiiatomic · covalent · van der Waals
Atomic (Empirical)
140.00pm
Covalent
116.00pm
Van der Waals
204.00pm
Electronic Propertieselectronegativity · ionization · affinity
Electron Configuration
[Ar] 3d6 4s2
Electron Shells
2, 8, 14, 2
Electronegativity
1.83Pauling
Electron Affinity
0.2kJ/mol
1st Ionization Energy
7.9kJ/mol
Oxidation States
-4, -2, -1, 0, +1, +2, +3, +4, +5, +6
Orbital DiagramAufbau · Hund's rule · Pauli exclusion
Full: 1s2 2s2 2p6 3s2 3p6 3d6 4s2Short: [Ar] 3d6 4s2
Ionization Energies (26 known)
Emission Spectrumvisible range · characteristic spectral lines
Abundanceby mass
Log scale · ppm = parts per million by mass
Biological Role
Core of hemoglobin and myoglobin for oxygen transport. Deficiency causes anemia.
Discovery
Discovered By
Known to the ancients.
Named By
—
Year
—
Nuclear Data
Known Isotopes
32
Stable Isotopes
4
Stable Mass Numbers
54, 56, 57, 58
Natural isotopic abundance (IUPAC recommended values)
Isotopes of Fe32 known
| Nuclide | Z | N | Mass (AMU) | Half-life | Decay | Jπ | Abundance |
|---|---|---|---|---|---|---|---|
| 45Fe | 26 | 19 | 45.015467 | 2.50 ms | 2p (0.7%), β⁺ (0.3%), β⁺p (0.18899999999999997%), 2p (0.078%) | 3/2+ | — |
| 46Fe | 26 | 20 | 46.001299 | 13.0 ms | β⁺ (1%), β⁺p (0.787%), 2p | 0+ | — |
| 47Fe | 26 | 21 | 46.992346 | 21.9 ms | β⁺ (1%), β⁺p (0.884%) | 7/2- | — |
| 54Festable | 26 | 28 | 53.939608 | Stable | 2β⁺ | 0+ | 584.5000% |
| 56Festable | 26 | 30 | 55.934936 | Stable | stable (1%) | 0+ | 9175.4000% |
| 57Festable | 26 | 31 | 56.935392 | Stable | stable (1%) | 1/2- | 211.9000% |
| 58Festable | 26 | 32 | 57.933274 | Stable | stable (1%) | 0+ | 28.2000% |
| 74Fe | 26 | 48 | 73.977821 | 5.00 ms | β⁻ (1%), β⁻n, 2n | 0+ | — |
| 75Fe | 26 | 49 | 74.984219 | Unknown | β⁻, β⁻n, 2n | 9/2+ | — |
| 76Fe | 26 | 50 | 75.988631 | Unknown | β⁻ | 0+ | — |