Iron is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core.
Iron is used in numerous sectors such as electronics, manufacturing, automotive, and construction and building. Iron is the most widely used of all the metals, accounting for over 90% of worldwide metal production.
The main mining areas for iron are China, Australia, Brazil, Russia, and Ukraine. Worlds annual iron ore production is about 1600 milion tonnes.
Protons and Neutrons in Iron
Iron is a chemical element with atomic number 26 which means there are 26 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Iron are 56; 57; 58.
Main Isotopes of Iron
Iron has four stable isotopes: 54Fe (5.845% of natural iron), 56Fe (91.754%), 57Fe (2.119%) and 58Fe (0.282%). 20-30 artificial isotopes have also been created.
Iron-54 is composed of 26 protons, 28 neutrons, and 26 electrons.
Iron-56 is composed of 26 protons, 30 neutrons, and 26 electrons.
Iron-57 is composed of 26 protons, 31 neutrons, and 26 electrons.
Iron-58 is composed of 26 protons, 32 neutrons, and 26 electrons.
Iron-56 is the most stable nucleus. It is most efficiently bound and has the lowest average mass per nucleon (930.412 MeV/c2). Nickel-62, iron-58 and iron-56 are the most tightly bound nuclei. It takes more energy per nucleon to take one of these nuclei completely apart than it takes for any other nucleus.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Iron is 26. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Iron is [Ar] 3d6 4s2.
Possible oxidation states are +2,3.
Its 26 electrons are arranged in the configuration [Ar]3d64s2, of which the 3d and 4s electrons are relatively close in energy, and thus it can lose a variable number of electrons and there is no clear point where further ionization becomes unprofitable.
Iron forms compounds mainly in the oxidation states +2 (iron(II), “ferrous”) and +3 (iron(III), “ferric”). Iron also occurs in higher oxidation states, e.g. the purple potassium ferrate (K2FeO4), which contains iron in its +6 oxidation state.
Most Common Alloy of Iron
Carbon steels are iron–carbon alloys that may contain appreciable concentrations of other alloying elements. Plain carbon steels are iron-carbon alloys in which the properties are primarily derived from the presence of carbon. Some incidental elements like manganese, silicon, sulphur and phosphorus are present in small amounts due to the method of making steels and, not to modify the mechanical properties. Adding a small amount of non-metallic carbon to iron trades its great ductility for the greater strength. Due to its very-high strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful and common ferrous alloy in modern use.
|Number of protons||26|
|Number of neutrons (typical isotopes)||56; 57; 58|
|Number of electrons||26|
|Electron configuration||[Ar] 3d6 4s2|
Properties of other elements