Search results
Results from the WOW.Com Content Network
Osmium is a hard, brittle, blue-gray metal, and the densest stable element—about twice as dense as lead. The density of osmium is slightly greater than that of iridium ; the two are so similar (22.587 versus 22.562 g/cm 3 at 20 °C) that each was at one time considered to be the densest element.
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.
Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility. Correspondingly, its bulk modulus is extremely high, reported between 395 and 462 GPa, which rivals that of diamond (443 GPa). The hardness of osmium is moderately high at 4 GPa.
Most definitions of the term 'refractory metals' list the extraordinarily high melting point as a key requirement for inclusion. By one definition, a melting point above 4,000 °F (2,200 °C) is necessary to qualify, which includes iridium, osmium, niobium, molybdenum, tantalum, tungsten, rhenium, rhodium, ruthenium and hafnium. [2]
The common oxide of carbon (CO 2) is a medium-strength acidic oxide. Silicon has a blue-grey metallic lustre. Silicon is a metallic-looking relatively unreactive solid with a density of 2.3290 g/cm 3, and is hard (MH 6.5) and brittle. It melts at 1414 °C (cf. steel ~1370 °C) and boils at 3265 °C. Silicon has a diamond cubic structure (CN 4).
Osmium(II) iodide is a black solid [35] produced by the reaction of osmium tetroxide and hydroiodic acid at 250 °C in nitrogen: [34] OsO 4 + HI → OsI 2 + H 2 O. This compound decomposes in contact with water. [35] Osmium(III) iodide is a black solid that is produced by heating hexaiodoosmic acid (H 2 OsI 6). [34] This compound is insoluble ...
Poison Profits. A HuffPost / WNYC investigation into lead contamination in New York City
The least brittle structural ceramics are silicon carbide (mainly by virtue of its high strength) and transformation-toughened zirconia. A different philosophy is used in composite materials, where brittle glass fibers, for example, are embedded in a ductile matrix such as polyester resin. When strained, cracks are formed at the glass–matrix ...