geologia: Magnesium

Evidence: 80 • authority: 72

The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals, and they are less reactive than the alkali metals at standard temperature and pressure. Together with helium, these elements have in common an outer s orbital which is full—that is, this orbital contains its full complement of two electrons, which the alkaline earth metals readily lose to form cations with charge +2, and an oxidation state of +2. Helium is grouped with the noble gases and not with the alk…

Evidence: 56 • authority: 88

Enforcing Metal‒Arene Interactions in Bulky p-Terphenyl Bis(anilide) Complexes of Group 2 Metals (Be‒Ba): Potential Precursors for Low Oxidation State Alkaline Earth Metal Systems. An extremely bulky p-terphenyl bis(aniline), p-C6H4{C6H4[N(H)TCHP]-2}2 (TCHP = 2,4,6-tricyclohexylphenyl) TCHPTerphH2, has been developed. Deprotonation of a less bulky analogue, DipTerphH2 (Dip = 2,6-diisopropylphenyl), with BePh2 affords the bimetallic system, [(BePh)2(-DipTerph)] 1. Treating either TCHPTerphH2 or DipTerphH2 with Mg{CH2(SiMe3)}2 gives the monomeric bis(anilide) complexes [Mg(ArTerph)] (Ar = Dip 2, TCHP 3) which display rare examples of eta-6-arene coordination to the metal centre. Treating 2 wi…

Evidence: 49 • authority: 72

An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 (called a passivation layer) that protects the foil from further oxidation.

Evidence: 48 • authority: 92

K<sub>5</sub>Ir: reduced iridium stabilized at high pressure.. Alkali binary compounds offer a way to expand our understanding of the periodic table. Specifically, the redox inert nature of alkali cations, even within some intermetallic compounds, enables one to access exotic oxidation states. Iridium presents a test case, as it is the transition metal best positioned to form a trianion, which would be the most highly charged transition metal anion reported. Pressure, known to modulate both reactivity and electronic structure to stabilize exotic phases, is a promising path to this species. Others predicted that reduction of Ir with alkali metals at high pressure may yield phases…

Evidence: 43 • authority: 80

Enforcing MetalArene Interactions in Bulky pTerphenyl Bis(anilide) Complexes of Group 2 Metals (BeBa): Potential Precursors for Low-Oxidation-State Alkaline Earth Metal Systems

Evidence: 43 • authority: 72

In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom assuming all of its bonds to other atoms are fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. In a binary compound like KCl, an oxidation state of +1 for K implies it has donated an electron to Cl, which will have an oxidation state of -1. Oxidation state is useful for estimating the distribution of electric charge within molecules, especially for those containing primarily ionic bonds, and less so for those with primarily covalent bonds. The oxidation state of an atom is cap…

Evidence: 36 • authority: 72

In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinide elements (the f-block) are called inner transition metals and are sometimes considered to be transition metals as well. They are lustrous metals with good electrical and thermal conductivity. Most (with the exception of group 11 and group 12) are hard and strong, and have high melting and boiling temperatures. They form compounds in any of two or more different oxidation states and bind to a variety of ligands to form coordination complexes that are of…

Evidence: 31 • authority: 72

The rare-earth elements (REE), also called rare-earth metals, or rare earths, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. The 15 lanthanides (or lanthanoids), along with scandium, and yttrium, are usually included as rare earths. Compounds containing rare-earth elements have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes. Rare-earths are to be distinguished from critical minerals, which are materials of strategic or economic importance that are defined differently by different countries, and rare-earth minerals, which are minerals that contain one or more rare-earth elements as…

Evidence: 25 • authority: 88

The alkaline and alkaline earth metals. This chapter focuses on Alkaline metal ions (sodium and potassium ions) and alkaline earth metal ions (magnesium and calcium ions), which play important roles in a plethora of physiological processes. It discusses the mechanisms that are responsible for steering and control of the ion concentrations in the extracellular space and the cytosolic cell compartments. It describes the four main transportation routes for alkaline and alkaline earth metal ions and tackles ion channels — the membrane-bound proteins which are gated by chemical, mechanical, electric, or light stimuli. The chapter also explains the concept of exchange kinetics. Furthermore, it lo…

Evidence: — • authority: 65