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Arsphenamine. The structure of arsphenamine has been proposed to be akin to azobenzene (A), but chemical studies published in 2005 suggest [1] that salvarsan is actually a mixture of the trimer (B) and the pentamer (C). Arsphenamine, also known as Salvarsan or compound 606, is an antibiotic drug that was introduced at the beginning of the 1910s ...
Elements often discussed as toxic include cadmium, mercury and lead, [6] all of which appear in the World Health Organization's list of 10 chemicals of major public concern. [7] Other examples include chromium and nickel, [8] thallium, bismuth, arsenic, antimony and tin. [4] These toxic elements are found naturally in the earth.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
He called U.S. policy thinking about Asia as "little promising" and "fraught with danger". About the Korean War, Kennan wrote that American policies were based upon what he called "emotional, moralistic attitudes" which "unless corrected, can easily carry us toward real conflict with the Russians and inhibit us from making a realistic agreement ...
Chemical property. A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any attribute that can be established only by changing a substance's chemical identity. [1] Simply speaking, chemical properties cannot be determined just by viewing or touching the substance; the ...
A more recent industrial standard is the European EN 13501-1 - Fire classification of construction products and building elements—which roughly replaces A2 with A2/B, B1 with C, B2 with D/E and B3 with F. B3 or F rated materials may not be used in building unless combined with another material that reduces the flammability of those materials.
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
v. t. e. The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in ...