Iron is an element that is essential for human life and found in pure form as well as alloys. It is found in hemoglobin in red blood cells and cast iron cookware. Here are interesting element facts about iron, a transition metal with the element symbol Fe and atomic number 26.
Interesting Iron Facts
- Iron has been used by humans for over 5,000 years. It has been found in ancient Egyptian artifacts as early as 3,500 BC. However, few ancient iron artifacts survived to the present day because of the metal’s tendency to corrode in water and air.
- The element symbol for iron, Fe, comes from Latin name for the element, “ferrum.” The modern name “iron” comes from the Anglo-Saxon word “iron” and the Scandinavian word “iarn.”
- Iron is a common element on Earth as well as throughout the universe. It is the fourth most abundant element in the Earth’s crust by mass (5.6%) and believed to be the most abundant element in the planet overall because it accounts for much of the mass of Earth’s inner and outer core. It is the sixth most abundant element in the universe. Iron is the heaviest element formed by fusion in stars.
- Iron is not always magnetic. The alpha allotrope is ferromagnetic, but the beta allotrope is not.
- Both animals and plants need iron. Plants use iron to produce chlorophyll, which in turn is used for photosynthesis. Human use iron in hemoglobin to transport oxygen to cells. Some bacteria use iron-sulfur clusters for nitrogen fixation.
- While iron is an essential nutrient, it is toxic in high amounts. Free iron reacts with peroxides to form free radicals in blood, which can damage protein, lipids, and DNA. Iron is considered to be toxic to people at a concentration of 20 mg per kg body weight and lethal at 60 mg per kg body weight.
- The most common oxidation states of iron are +2 and +3, but several other states are possible.
Natural iron consists of four stable isotopes. Of these, iron-56 is the most abundant, accounting for 91.75% of the element. Only iron-57 has a nuclear spin. Numerous radioisotopes have been produced (at least 14).
- There are four allotropes or forms of iron. They are collectively known as “ferrites” and are named the α-, β-, γ-, and δ-allotropes. While the alpha and beta forms have the same crystal structure, they exhibit different properties.
- Freshly prepared iron is metallic silver, but the element rapidly oxidizes to develop a black coating. Iron burns golden yellow in a flame test. The metal is used in fireworks for this golden color, plus it produces sparks ranging in color from red to yellow to white based on the metal’s temperature.
Iron Atomic Data
Element Symbol: Fe
- Atomic Number: 26
- Standard Atomic Weight: 55.845(2)
- Appearance: Grayish-silver metal
- Group: Group 8 (transition metal)
- Period: Period 4
- Block: d-block
- Electron Configuration: [Ar]3d64s2
- Phase at STP: solid
- Melting Point: 1811 K (1538 °C, 2800 °F)
- Boiling Point: 3134 K (2862 °C, 5182 °F)
- Density: 7.874 g/cm3 (near room temperature)
- Oxidation States: -4, -2, -1, +1, +2, +3, +4, +5, +6, +7 (bold most common)
- Electronegativity: 1.83 (Pauling scale)
- Ionization Energies: 1st: 762.5 kJ/mol; 2nd: 1561.9 kJ/mol; 3rd: 2957 kJ/mol
- Atomic Radius: 126 pm (empirical)
- Crystal Structure: body-centered cubic or face-centered cubic
- Mohs Hardness: 4
- Discovery: Before 5000 BC
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