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Four allotropes (structural forms) of solid manganese are known, labeled α, β, γ and δ, and occurring at successively higher temperatures. All are metallic, stable at standard pressure, and have a cubic crystal lattice, but they vary widely in their atomic structures. [18] [19] [20] Alpha manganese (α-Mn) is the equilibrium phase at room ...
The pnictogens exemplify the transition from nonmetal to metal going down the periodic table: a gaseous diatomic nonmetal (N), two elements displaying many allotropes of varying conductivities and structures (P and As), and then at least two elements that only form metallic structures in bulk (Sb and Bi; probably Mc as well).
These allotropes are known as the amorphous and the crystalline allotropes. The amorphous allotrope is a brown powder. The crystalline allotrope is gray and has a metallic luster. [16] Tin has two allotropes: α-tin, also known as gray tin, and β-tin. Tin is typically found in the β-tin form, a silvery metal.
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.. Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other' and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements.
Naturally occurring manganese (25 Mn) is composed of one stable isotope, 55 Mn. Twenty-seven radioisotopes have been characterized, with the most stable being 53 Mn with a half-life of 3.7 million years, 54 Mn with a half-life of 312.3 days, and 52 Mn with a half-life of 5.591 days.
Manganese is also important in photosynthetic oxygen evolution in chloroplasts in plants. The oxygen-evolving complex (OEC) is a part of photosystem II contained in the thylakoid membranes of chloroplasts; it is responsible for the terminal photooxidation of water during the light reactions of photosynthesis , and has a metalloenzyme core ...
Manganese nitrides are salts of manganese and the nitride ion. Four of these compounds are stable at atmospheric pressure . The most important is Mn 3 N 2 , which catalyzes nitrogen fixation and is a high-temperature antiferromagnet .
Manganese is a necessary element for biological functions such as photosynthesis, and some manganese oxidizing bacteria utilize this element in anoxic environments. [2] [3] Movement of manganese (Mn) among the global "spheres" (described below) is mediated by both physical and biological processes.