Manganese

**Characteristics of Manganese**:
– Manganese is a silvery-gray metal resembling iron.
– It is hard, brittle, and easily oxidizes.
– Manganese and its ions are paramagnetic.
– Manganese tarnishes in air and rusts in water.
– Four allotropes of solid manganese are known, labeled α, β, γ, and δ.
– Manganese slowly tarnishes in air and oxidizes like iron in water.

**Isotopes and Allotropes of Manganese**:
– Naturally occurring manganese has one stable isotope.
– Several radioisotopes of manganese have been identified.
– Mn decays to Cr with a half-life of 3.7 million years.
– Manganese isotopic contents are used in isotope geology.
– Mn provides evidence for nucleosynthetic processes in the Solar System.
– Four allotropes of solid manganese are known, with alpha manganese being the equilibrium phase at room temperature.

**Chemical Compounds and Industrial Applications**:
– Common oxidation states of manganese are +2, +3, +4, +6, and +7.
– Potassium permanganate is a common laboratory reagent.
– Manganese compounds have historical usage in glassmaking and were isolated by Johan Gottlieb Gahn.
– Manganese is essential in iron and steel production for its properties.
– Manganese alloyed with iron was found to be harder without increased brittleness.
– Manganese was introduced to steelmaking by Robert Forester Mushet in 1856.

**Organomanganese Compounds**:
– Manganese forms organometallic derivatives with Mn-C bonds in lower oxidation states.
– Mn is inexpensive and relatively low in toxicity, making it attractive in organometallic chemistry.
– The name ‘manganese’ has a complex origin from ancient times.
– Manganese dioxide has been used as a pigment for cave paintings.
– Manganese compounds have historical usage in glassmaking and were isolated by Johan Gottlieb Gahn.

**Occurrence and Historical Applications**:
– Manganese is the 12th most abundant element in the Earth’s crust.
– Soil contains an average of 440ppm of manganese.
– Manganese occurs mainly as pyrolusite, braunite, and rhodochrosite.
– South Africa holds about 80% of the world’s known manganese resources.
– Manganese dioxide was historically used in glassmaking, batteries, and as a pigment.

Manganese (Wikipedia)

Not to be confused with magnesium (Mg).

For other uses, see Manganese (disambiguation).

Manganese is a chemical element; it has symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. Manganese is a transition metal with a multifaceted array of industrial alloy uses, particularly in stainless steels. It improves strength, workability, and resistance to wear. Manganese oxide is used as an oxidising agent; as a rubber additive; and in glass making, fertilisers, and ceramics. Manganese sulfate can be used as a fungicide.

Manganese, ₂₅Mn

Pure manganese cube and oxidized manganese chips
Manganese
Pronunciation	/ˈmæŋɡəniːz/ ​(MANG-gə-neez)
Appearance	silvery metallic
Standard atomic weight Ar°(Mn)
	54.938043±0.000002 54.938±0.001 (abridged)
Manganese in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson – ↑ Mn ↓ Tc chromium ← manganese → iron
Atomic number (Z)	25
Group	group 7
Period	period 4
Block	d-block
Electron configuration	[Ar] 3d5 4s2
Electrons per shell	2, 8, 13, 2
Physical properties
Phase at STP	solid
Melting point	1519 K ​(1246 °C, ​2275 °F)
Boiling point	2334 K ​(2061 °C, ​3742 °F)
Density (near r.t.)	7.21 g/cm3
when liquid (at m.p.)	5.95 g/cm3
Heat of fusion	12.91 kJ/mol
Heat of vaporization	221 kJ/mol
Molar heat capacity	26.32 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1228 1347 1493 1691 1955 2333
Atomic properties
Oxidation states	−3, −1, 0, +1, +2, +3, +4, +5, +6, +7 (depending on the oxidation state, an acidic, basic, or amphoteric oxide)
Electronegativity	Pauling scale: 1.55
Ionization energies	1st: 717.3 kJ/mol 2nd: 1509.0 kJ/mol 3rd: 3248 kJ/mol (more)
Atomic radius	empirical: 127 pm
Covalent radius	Low spin: 139±5 pm High spin: 161±8 pm
Spectral lines of manganese
Other properties
Natural occurrence	primordial
Crystal structure	α-Mn: ​body-centered cubic (bcc) (cI58)
Lattice constant	a = 891.16 pm (at 20 °C)
Thermal expansion	21.7 µm/(m⋅K) (at 25 °C)
Thermal conductivity	7.81 W/(m⋅K)
Electrical resistivity	1.44 µΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic
Molar magnetic susceptibility	(α) +529.0×10−6 cm3/mol (293 K)
Young's modulus	198 GPa
Bulk modulus	120 GPa
Speed of sound thin rod	5150 m/s (at 20 °C)
Mohs hardness	6.0
Brinell hardness	196 MPa
CAS Number	7439-96-5
History
Discovery	Carl Wilhelm Scheele (1774)
First isolation	Johann Gottlieb Gahn (1774)
Isotopes of manganese v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 52Mn synth 5.591 d β+ 52Cr 53Mn trace 3.7×106 y ε 53Cr 54Mn synth 312.081 d ε 54Cr β− 54Fe β+ 54Cr 55Mn 100% stable
Category: Manganese view talk edit | references

Manganese is also an essential human dietary element, important in macronutrient metabolism, bone formation, and free radical defense systems. It is a critical component in dozens of proteins and enzymes. It is found mostly in the bones, but also the liver, kidneys, and brain. In the human brain, the manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes.

It is familiar in the laboratory in the form of the deep violet salt potassium permanganate. It occurs at the active sites in some enzymes. Of particular interest is the use of a Mn-O cluster, the oxygen-evolving complex, in the production of oxygen by plants.