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Origin of title phenomenon in crystallographic defects. Shown is a two-dimensional slice through a primitive cubic crystal system showing the regular square array of atoms on one face (open circles, o), and with these, places where atoms are missing from a regular site to create vacancies, displaced to an adjacent acceptable space to create a Frenkel pair, or substituted by a smaller or larger ...
The gas used is usually inert, or of a nature that protects the integrity of the packaged goods, inhibiting unwanted chemical reactions such as food spoilage or oxidation. Some may also serve as a propellant for aerosol sprays like cans of whipped cream. For packaging food, the use of various gases is approved by regulatory organisations. [1]
Highly Toxic: a gas that has a LC 50 in air of 200 ppm or less. [2] NFPA 704: Materials that, under emergency conditions, can cause serious or permanent injury are given a Health Hazard rating of 3. Their acute inhalation toxicity corresponds to those vapors or gases having LC 50 values greater than 1,000 ppm but less than or equal to 3,000 ppm ...
The trichlorosilane is then converted to a mixture of silane and silicon tetrachloride: 4 HSiCl 3 → SiH 4 + 3 SiCl 4. This redistribution reaction requires a catalyst. The most commonly used catalysts for this process are metal halides, particularly aluminium chloride. This is referred to as a redistribution reaction, which is a double ...
Right: Yttrium carbonate is soluble in excess alkali metal carbonate solution. As a trivalent transition metal, yttrium forms various inorganic compounds, generally in the +3 oxidation state, by giving up all three of its valence electrons. [21] A good example is yttrium(III) oxide (Y 2 O 3), also known as yttria, a six-coordinate white solid. [22]
Under normal conditions germanium tetraiodide (GeI 4) is a solid, germanium tetrafluoride (GeF 4) a gas and the others volatile liquids. For example, germanium tetrachloride, GeCl 4, is obtained as a colorless fuming liquid boiling at 83.1 °C by heating the metal with chlorine. [36]
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.
The alkaline earth metals (Be, Mg, Ca, Sr, Ba, and Ra) are the second most reactive metals in the periodic table, and, like the Group 1 metals, have increasing reactivity with increasing numbers of energy levels. Beryllium (Be) is the only alkaline earth metal that does not react with water or steam, even if the metal is heated red hot. [9]