Search results
Results from the WOW.Com Content Network
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.
Compounds of the metallic elements usually form simple aqua ions with the formula [M(H 2 O) n] z+ in low oxidation states. With the higher oxidation states the simple aqua ions dissociate losing hydrogen ions to yield complexes that contain both water molecules and hydroxide or oxide ions, such as the vanadium (IV) species [VO(H 2 O) 5 ] 2+ .
The mononuclear Mo enzymes are widely distributed in the biosphere; they catalyze many significant reactions in the metabolism of nitrogen and sulfur-containing compounds as well as various carbonyl compounds (e.g., aldehydes, CO, and CO 2). Nitrate reductases enzymes are important for the nitrogen cycle.
Metal ions and metallic compounds are often used in medical treatments and diagnoses. [18] Compounds containing metal ions can be used as medicine, such as lithium compounds and auranofin. [19] [20] Metal compounds and ions can also produce harmful effects on the body due to the toxicity of several types of metals. [18]
An intermetallic compound is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. [20] [21] [22] They can be classified as stoichiometric or nonstoichiometric intermetallic compounds. [20]
Zinc, as an abundant trace element, ranks sixth among all the essential metallic elements crucial for sustaining life within the human body. [61] Zinc exhibits an intermediate biodegradation rate, falling between that of Fe (relatively slow) and Mg (relatively high) which positions it as a promising material for use in biodegradable implants.
Several non-metallic elements exist only as molecules in the environment either in compounds or as homonuclear molecules, not as free atoms: for example, hydrogen. While some people say a metallic crystal can be considered a single giant molecule held together by metallic bonding , [ 20 ] others point out that metals behave very differently ...
The chemistry of astatine in aqueous solution is mainly characterised by the formation of various anionic species. [484] Most of its known compounds resemble those of iodine, [485] which is a halogen and a nonmetal. [486] Such compounds include astatides (XAt), astatates (XAtO 3), and monovalent interhalogen compounds. [487]