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Hammond's postulate (or alternatively the Hammond–Leffler postulate), is a hypothesis in physical organic chemistry which describes the geometric structure of the transition state in an organic chemical reaction. [1] First proposed by George Hammond in 1955, the postulate states that: [2]
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC, EDAC or EDCI) is a water-soluble carbodiimide usually handled as the hydrochloride. [1]It is typically employed in the 4.0-6.0 pH range.
Energeticism – a theory that attempted to reinterpret all chemistry in terms of energy, rejecting the concept of atoms. Caloric theory – the theory that a self-repelling fluid called "caloric" was the substance of heat. Rendered obsolete by the mechanical theory of heat.
By the 50th anniversary in 1988 some 40 million copies of the Teach Yourself series had been sold, with the books generating a turnover of over £1 million. [8] The author, Nigel Cumberland, of a Teach Yourself book entitled Secrets of Success at Work. Like many similar series, Teach Yourself has always used a common design for all of its books ...
Chemistry education is important because the field of chemistry is fundamental to our world. The universe is subject to the laws of chemistry, while human beings depend on the orderly progress of chemical reactions within their bodies. [2] Described as the central science, chemistry connects physical sciences with the life sciences and applied ...
Bill Belichick contacted the New York Jets about their head coaching vacancy before accepting the job at North Carolina, according to a person familiar with the situation. The 72-year-old ...
In physics and chemistry, a selection rule, or transition rule, formally constrains the possible transitions of a system from one quantum state to another. Selection rules have been derived for electromagnetic transitions in molecules, in atoms, in atomic nuclei, and so on. The selection rules may differ according to the technique used to ...
The number of migrants arrested illegally crossing the U.S.-Mexico border in December was lower than when President-elect Donald Trump ended his first term in 2020, according to preliminary ...