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Thegn. Ivory seal of Godwin, an unknown thegn – first half of eleventh century, British Museum. In later Anglo-Saxon England, a thegn ( pronounced / θeɪn /; Old English: þeġn) or thane [1] (or thayn in Shakespearean English) was an aristocrat who owned substantial land in one or more counties. Thanes ranked at the third level in lay ...
Chemical nomenclature. Chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC). IUPAC Nomenclature ensures that each compound (and its various isomers) have only ...
The Geneva Nomenclature of 1892 was created as a result of many other meetings in the past, the first of which was established in 1860 by August Kekulé. Another entity called the International Association of Chemical Societies (IACS) existed, and on 1911, gave vital propositions the new one should address: [ 2] Measures required to prevent ...
The protoscience of chemistry, and alchemy, was unsuccessful in explaining the nature of matter and its transformations. However, by performing experiments and recording the results, alchemists set the stage for modern chemistry. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard ...
This book is a collection of names and terms already discussed in Pure and Applied Chemistry. [57] The Compendium of Chemical Terminology was first published in 1987. [11] The first edition of this book contains no original material, but is meant to be a compilation of other IUPAC works. The second edition of this book was published in 1997. [31]
Polyurethane ( / ˌpɒliˈjʊərəˌθeɪn, - jʊəˈrɛθeɪn /; [ 1] often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials.
Imperial, royal, noble,gentry and chivalric ranks in Europe. Thane ( / ˈθeɪn /; Scottish Gaelic: taidhn) [ 1] was the title given to a local royal official in medieval eastern Scotland, equivalent in rank to the son of an earl, [ 2] who was at the head of an administrative and socio-economic unit known as a thanedom or thanage.
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.