| Iron | … |
|---|---|
| Pronunciation | /ˈaɪərn/ |
| Allotropes | see Allotropes of iron |
| Appearance | lustrous metallic with a grayish tinge |
| Standard atomic weight A °(Fe) | … |
| • 55.845 ± 0.002 1 • 55.845 ± 0.002 (abridged) 2 | |
| Iron in the periodic table | … |
| – ↑ Fe ↓ Ru manganese ← iron → cobalt | … |
| Atomic number (Z) | 26 |
| Group | group 8 |
| Period | period 4 |
| Block | d-block |
| Electron configuration | [Ar] 3d 4s |
| Electrons per shell | 2, 8, 14, 2 |
| Physical properties | … |
| Phase at STP | solid |
| Melting point | 1811 K (1538 °C, 2800 °F) |
| Boiling point | 3134 K (2861 °C, 5182 °F) |
| Density (at 20° C) | 7.874 g/cm 3 |
| when liquid (at m.p.) | 6.98 g/cm |
| Heat of fusion | 13.81 kJ/mol |
| Heat of vaporization | 340 kJ/mol |
| Molar heat capacity | 25.10 J/(mol·K) |
| Specific heat capacity | 449.458 J/(kg·K) |
| Vapor pressure | … |
| Atomic properties | … |
| Oxidation states | common: +2, +3 −2,4 −1,4 0,4 +1,5 +4,4 +5,6 +6,4 +77 |
| Electronegativity | Pauling scale: 1.83 |
| Ionization energies | • 1st: 762.5 kJ/mol • 2nd: 1561.9 kJ/mol • 3rd: 2957 kJ/mol • (more) |
| Atomic radius | empirical: 126 pm |
| Covalent radius | Low spin: 132±3 pm High spin: 152±6 pm |
| Van der Waals radius | 194 [1] pm |
| Spectral lines of iron | … |
| Other properties | … |
| Natural occurrence | primordial |
| Crystal structure | α-Fe: body-centered cubic (bcc) (cI2) |
| Lattice constant | a = 286.65 pm (at 20 °C)3 |
| Crystal structure | γ-Fe (912–1394 °C): face-centered cubic (fcc) (cF4) |
| Lattice constant | a = 364.68 pm (at 916 °C)8 |
| Thermal expansion | 12.07×10/K (at 20 °C)3 |
| Thermal conductivity | 80.4 W/(m⋅K) |
| Electrical resistivity | 96.1 nΩ⋅m (at 20 °C) |
| Curie point | 1043 K |
| Magnetic ordering | ferromagnetic |
| Young’s modulus | 211 GPa |
| Shear modulus | 82 GPa |
| Bulk modulus | 170 GPa |
| Speed of sound thin rod | 5120 m/s (at r.t.) (electrolytic) |
| Poisson ratio | 0.29 |
| Mohs hardness | 4 |
| Vickers hardness | 608 MPa |
| Brinell hardness | 200–1180 MPa |
| CAS Number | 7439-89-6 |
| History | … |
| Naming | probably from a PIE root meaning ‘blood’, for the color of its oxides |
| Discovery | before 5000 BC |
| Symbol | ”Fe”: from Latin ferrum |
| Isotopes of iron | … |
Iron, Fe
(echo:: @ ᯤ)
Footnotes
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“Standard Atomic Weights: Iron”. CIAAW. 1993. ↩
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Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). “Standard atomic weights of the elements 2021 (IUPAC Technical Report)”. Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075. ↩
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Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9. ↩ ↩2 ↩3
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Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8. ↩ ↩2 ↩3 ↩4 ↩5
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Ram, R. S.; Bernath, P. F. (2003). “Fourier transform emission spectroscopy of the gΔ–aΔ system of FeCl”. Journal of Molecular Spectroscopy. 221 (2): 261. Bibcode:2003JMoSp.221..261R. doi:10.1016/S0022-2852(03)00225-X. ↩
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Demazeau, G.; Buffat, B.; Pouchard, M.; Hagenmuller, P. (1982). “Recent developments in the field of high oxidation states of transition elements in oxides stabilization of six-coordinated Iron(V)”. Zeitschrift für anorganische und allgemeine Chemie. 491: 60–66. doi:10.1002/zaac.19824910109. ↩
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Lu, J.; Jian, J.; Huang, W.; Lin, H.; Li, J; Zhou, M. (2016). “Experimental and theoretical identification of the Fe(VII) oxidation state in FeO_{4}$$^{−}”. Physical Chemistry Chemical Physics. 18 (45): 31125–31131. Bibcode:2016PCCP…1831125L. doi:10.1039/C6CP06753K. PMID 27812577. ↩
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Cardarelli, François (2008). Materials Handbook: A Concise Desktop Reference. London: Springer. p. 65. ISBN 1-84628-668-9. ↩