What is Iron atom?

     

Iron is a chemical element with symbol Fe and atomic number 26.  It is a metal that belongs to the first transition series and group 8 of the periodic table.  It is by mass the most common element on Earth, right in front of oxygen forming mush of Earth's outer and inner core.  It is the fourth most common element in the Earth's crust.

     In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites.  Iron ores, by contrast, are among the most abundant in the Earth's crust, although kilns or furnaces capable of reaching 1,500︒C or higher, about 500︒C higher than that required to smelt copper.  Humans started to master that process in Eurasia only about 2000 BCE, and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE.  That event is considered the transition  from the Bronze Age to the Iron Age.  

    In the modern world, iron alloys such as steel, inox, cast iron and special steels are by far the most common industrial metals, because of their mechanical properties and low cost.  Pristine and smoooth pure iron surgaces are mirror-like silvery-gray.  However, iron reacts readily with oxygen and water to give brown to black hydrated iron oxides commonly known as rust.  Unlike the oxides of some other metals, that form passivating layers, rust occupies more volume than the metal and thus flakes off, exposing fresh surfaces for corrosion.   

     Chemically, the most common oxidation states of iron are iron(ii) and iron(iii).  Iron shares many properties of other transition metals, including the other group 8 elements, ruthenium and osmium.  Iron forms compounds in a wide range of oxidation states,-2 to +7.  Iron also forms many coordination compounds; some of them, such as ferrocene, ferrioxalate, and Prussian blue, have substantial industrial medical or research application.