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List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. 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]
Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.
In historical linguistics, Weise's law describes the loss of palatal quality some consonants undergo in specific contexts in the Proto-Indo-European language.In short, when the consonants represented by *ḱ *ǵ *ǵʰ, called palatovelar consonants, are followed by *r, they lose their palatal quality, leading to a loss in distinction between them and the plain velar consonants *k *g *gʰ.
ChemSpider. ChemSpider is a freely accessible online database of chemicals owned by the Royal Society of Chemistry. [3][4][5][6][7] It contains information on more than 100 million molecules from over 270 data sources, each of them receiving a unique identifier called ChemSpider Identifier.
List of online encyclopedias. This is a list of well-known online encyclopedias that are accessible or formerly accessible on the Internet. The largest online encyclopedias are general reference works, though there are also many specialized ones. Some online encyclopedias are editions of a print encyclopedia, such as Encyclopædia Britannica ...
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other ...
The first edition of the Merck's Index was published in 1889 by the German chemical company Emanuel Merck and was primarily used as a sales catalog for Merck's growing list of chemicals it sold. [2] The American subsidiary was established two years later and continued to publish it. During World War I the US government seized Merck's US ...
The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. [6]