Science, Tech, Math › Science Iron Facts Chemical & Physical Properties of Iron Share Flipboard Email Print dt03mbb / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated October 03, 2019 Iron Basic Facts: Symbol: FeAtomic Number: 26Atomic Weight: 55.847Element Classification: Transition MetalCAS Number: 7439-89-6 Iron Periodic Table Location Group: 8Period:4Block: d Iron Electron Configuration Short Form: [Ar]3d64s2Long Form: 1s22s22p63s23p63d64s2Shell Structure: 2 8 14 2 Iron Discovery Discovery Date: Ancient TimesName: Iron derives its name from the Anglo-Saxon 'iren'. The element symbol, Fe, was shortened from the Latin word 'ferrum' meaning 'firmness'.History: Ancient Egyptian iron objects have been dated to around 3500 B.C. These objects also contain approximately 8% nickel showing the iron may have originally been part of a meteorite. The "Iron Age" began around 1500 B.C. when the Hittites of Asia Minor began to smelt iron ore and make iron tools. Iron Physical Data State at room temperature (300 K): SolidAppearance: malleable, ductile, silvery metalDensity: 7.870 g/cc (25 °C)Density at Melting Point: 6.98 g/ccSpecific Gravity: 7.874 (20 °C)Melting Point: 1811 KBoiling Point: 3133.35 KCritical Point: 9250 K at 8750 barHeat of Fusion: 14.9 kJ/molHeat of Vaporization: 351 kJ/molMolar Heat Capacity: 25.1 J/mol·KSpecific Heat: 0.443 J/g·K (at 20 °C) Iron Atomic Data Oxidation States (Bold most common): +6, +5, +4, +3, +2, +1, 0, -1, and -2Electronegativity: 1.96 (for oxidation state +3) and 1.83 (for oxidation state +2)Electron Affinity: 14.564 kJ/molAtomic Radius: 1.26 ÅAtomic Volume: 7.1 cc/molIonic Radius: 64 (+3e) and 74 (+2e)Covalent Radius: 1.24 ÅFirst Ionization Energy: 762.465 kJ/molSecond Ionization Energy: 1561.874 kJ/molThird Ionization Energy: 2957.466 kJ/mol Iron Nuclear Data Number of isotopes: 14 isotopes are known. Naturally occuring iron is made up of four isotopes.Natural Isotopes and % abundance: 54Fe (5.845),56Fe (91.754), 57Fe (2.119) and 58Fe (0.282) Iron Crystal Data Lattice Structure: Body-Centered CubicLattice Constant: 2.870 ÅDebye Temperature: 460.00 K Iron Uses Iron is vital to plant and animal life. Iron is the active part of the hemoglobin molecule our bodies use to transport oxygen from the lungs to the rest of the body. Iron metal is widely alloyed with other metals and carbon for a multiple commercial uses. Pig iron is an alloy containing about 3-5% carbon, with varying quantities of Si, S, P, and Mn. Pig iron is brittle, hard, and fairly fusible and is used to produce other iron alloys, including steel. Wrought iron contains only a few tenths of a percent of carbon and is malleable, tough, and less fusible than pig iron. Wrought iron typically has a fibrous structure. Carbon steel is an iron alloy with carbon and small amounts of S, Si, Mn, and P. Alloy steels are carbon steels that contain additives such as chromium, nickel, vanadium, etc. Iron is the least expensive, most abundant, and most used of all metals. Miscellaneous Iron Facts Iron is the 4th most abundant element in the Earth's crust. The Earth's core is believed to be comprised primarily of iron.Pure iron is chemically reactive and corrodes rapidly, especially in moist air or at elevated temperatures.There are four allotropes of iron known as 'ferrites'. These are designated α-, β-, γ-, and δ- with transition points at 770, 928, and 1530 °C. The α- and β- ferrites have the same crystal structure, but when the α- form becomes the β- form, the magnetism disappears.The most common iron ore is hematite (Fe2O3 mostly). Iron is also found in magnetite (Fe3O4) and taconite (a sedimentary rock containing more than 15% iron mixed with quartz).The top three countries that mine iron are Ukraine, Russia and China. China, Australia and Brazil lead the world in iron production.Many meteorites have been found to contain high levels of iron.Iron is found in the sun and other stars.Iron is an essential mineral for health, but too much iron is extremely toxic. Free iron in the blood reacts with peroxides to form free radicals that damage DNA, protein, lipids and other cellular components, leading to illness and sometimes death. 20 milligrams of iron per kilogram of body weight is toxic, while 60 milligrams per kilogram is lethal.Iron is essential for the development of brain development. Children with iron deficiencies show a lower ability to learn.Iron burns with a gold color in a flame test.Iron is used in fireworks to make sparks. The color of the sparks will depend on the temperature of the iron. Sources CRC Handbook of Chemistry & Physics (89th Ed.), National Institute of Standards and Technology, History of the Origin of the Chemical Elements and Their Discoverers, Norman E. Holden 2001.