Search results
Results from the WOW.Com Content Network
The structure of hemoglobin.The heme cofactor, containing the metal iron, shown in green.. Metalloprotein is a generic term for a protein that contains a metal ion cofactor. [1] [2] A large proportion of all proteins are part of this category.
The heteropolymetalates form distinct structures because the main group center is usually tetrahedral. The Lindqvist and Keggin structures are common motifs for iso- and heteropolyanions, respectively. Polyoxometalates typically exhibit coordinate metal-oxo bonds of different multiplicity and
The structure of binary oxides can be predicted on the basis of the relative sizes of the metal and oxide ions and the filling of holes in a close packed oxide lattice. However, the predictions of structure are more difficult for ternary oxides. The combination of two or more metals in an oxide creates a lot of structural possibilities.
The structure is inverse spinel, with O 2-ions forming a face-centered cubic lattice and iron cations occupying interstitial sites. Half of the Fe 3+ cations occupy tetrahedral sites while the other half, along with Fe 2+ cations, occupy octahedral sites. The unit cell consists of thirty-two O 2-ions and unit cell length is a = 0.839 nm. [15] [16]
The body-centered cubic and monoclinic forms are the most common polymorphic forms of curium trioxide, produced by the chemical reactions detailed above. Their crystalline structures are very similar. One of the polymorphs of curium trioxide - the body-centered cubic form - spontaneously transforms to the hexagonal form after several weeks. [8]
Iron silicate, Fe 2 SiO 4, the mineral fayalite, is one of many examples of a ternary oxide. For many metal oxides, the possibilities of polymorphism and nonstoichiometry exist as well. [3] The commercially important dioxides of titanium exists in three distinct structures, for example. Many metal oxides exist in various nonstoichiometric states.
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Oxide precursors are not required to have the same crystal structure as the desired HEO for the solid-state reaction method to be effective. For example, CuO and ZnO may be used as precursors to synthesize (MgNiCuCoZn) 0.2 O. At room temperature, CuO has the tenorite structure and ZnO has the wurtzite structure.