Manganese
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.
Not to be confused with magnesium (Mg).Manganese
silvery metallic
$_$_$DEEZ_NUTS#1__answer--2DEEZ_NUTS$_$_$
25
[Ar] 3d5 4s2
2, 8, 13, 2
1519 K (1246 °C, 2275 °F)
2334 K (2061 °C, 3742 °F)
7.21 g/cm3
5.95 g/cm3
12.91 kJ/mol
221 kJ/mol
26.32 J/(mol·K)
−3, −1, 0, +1, +2, +3, +4, +5, +6, +7 (depending on the oxidation state, an acidic, basic, or amphoteric oxide)
Pauling scale: 1.55
- 1st: 717.3 kJ/mol
- 2nd: 1509.0 kJ/mol
- 3rd: 3248 kJ/mol
- (more)
empirical: 127 pm
Low spin: 139±5 pm
High spin: 161±8 pm
α-Mn: body-centered cubic (bcc) (cI58)
21.7 µm/(m⋅K) (at 25 °C)
7.81 W/(m⋅K)
1.44 µΩ⋅m (at 20 °C)
paramagnetic
(α) +529.0×10−6 cm3/mol (293 K)[4]
198 GPa
120 GPa
5150 m/s (at 20 °C)
6.0
196 MPa
7439-96-5
Carl Wilhelm Scheele (1774)
Johann Gottlieb Gahn (1774)
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.[6] It is found mostly in the bones, but also the liver, kidneys, and brain.[7] 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.[8] Of particular interest is the use of a Mn-O cluster, the oxygen-evolving complex, in the production of oxygen by plants.
Characteristics[edit]
Physical properties[edit]
Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, but easy to oxidize.[9] Manganese metal and its common ions are paramagnetic.[10] Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen.
Exposure[edit]
In water[edit]
Waterborne manganese has a greater bioavailability than dietary manganese. According to results from a 2010 study,[104] higher levels of exposure to manganese in drinking water are associated with increased intellectual impairment and reduced intelligence quotients in school-age children. It is hypothesized that long-term exposure due to inhaling the naturally occurring manganese in shower water puts up to 8.7 million Americans at risk.[105] However, data indicates that the human body can recover from certain adverse effects of overexposure to manganese if the exposure is stopped and the body can clear the excess.[106]
Mn levels can increase in seawater is when hypoxic periods occur.[107] Since 1990 there have been reports of Mn accumulation in marine organisms including fish, crustaceans, mollusks, and echinoderms. Specific tissues are targets in different species, including the gills, brain, blood, kidney, and liver/hepatopancreas. Physiological effects have been reported in these species. Mn can affect the renewal of immunocytes and their functionality, such as phagocytosis and activation of pro-phenoloxidase, suppressing the organisms' immune systems. This causes the organisms to be more susceptible to infections. As climate change occurs, pathogen distributions increase, and in order for organisms to survive and defend themselves against these pathogens, they need a healthy, strong immune system. If their systems are compromised from high Mn levels, they will not be able to fight off these pathogens and die.[65]