|
Jean Stas
Jean Servais Stas (21 August 1813 – 13 December 1891) was a Belgian analytical chemist who accurately measured the atomic weight of carbon. Life and work Stas was born in Leuven and trained initially as a physician. He later switched to chemistry and worked at the École Polytechnique in Paris under the direction of Jean-Baptiste Dumas. Stas and Dumas established the atomic weight of carbon by weighing a sample of the pure material, burning it in pure oxygen, and then weighing the carbon dioxide produced. In 1840, Stas was appointed professor at the Royal Military Academy (Belgium), Royal Military School in Brussels. He acquired international fame by determining the atomic weights of the Element (chemistry), elements more accurately than had ever been done before, using an atomic mass of 16 for oxygen as his standard. His results disproved the hypothesis of the English physicist William Prout that all atomic weights must be integer multiples of that of hydrogen. These carefu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leuven
Leuven (, , ), also called Louvain (, , ), is the capital and largest City status in Belgium, city of the Provinces of Belgium, province of Flemish Brabant in the Flemish Region of Belgium. It is located about east of Brussels. The municipality itself comprises the deelgemeente, sub-municipalities of Heverlee, Kessel-Lo, Leuven proper, Wilsele, Wijgmaal and part of Haasrode, Leuven, Haasrode and Korbeek-Lo, Leuven, Korbeek-Lo. It is the eighth largest city in Belgium, with more than 100,244 inhabitants. Leuven has been a university city since 1425. This makes it the oldest university city in the Low Countries. KU Leuven, the largest Dutch-speaking university in the world and the largest university in the Low Countries (and thus also Belgium's largest university), has its flagship campus in Leuven. The city is home of the headquarters of Anheuser-Busch InBev, the world's largest beer brewer and sixth-largest fast-moving consumer goods company. History Middle Ages The earli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Mass
Atomic mass ( or ) is the mass of a single atom. The atomic mass mostly comes from the combined mass of the protons and neutrons in the nucleus, with minor contributions from the electrons and nuclear binding energy. The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to mass defect (explained by mass-energy equivalence: ). Atomic mass is often measured in dalton (Da) or unified atomic mass unit (u). One dalton is equal to the mass of a carbon-12 atom in its natural state, given by the atomic mass constant , where is the atomic mass of carbon-12. Thus, the numerical value of the atomic mass of a nuclide when expressed in daltons is close to its mass number. The relative isotopic mass (see section below) can be obtained by dividing the atomic mass of an isotope by the atomic mass constant , yielding a dimensionless value. Thus, the atomic mass of a carbon-12 atom is b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society Of London
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, education and public engagement and fostering international and global co-operation. Founded on 28 November 1660, it was granted a royal charter by King Charles II and is the oldest continuously existing scientific academy in the world. The society is governed by its Council, which is chaired by the society's president, according to a set of statutes and standing orders. The members of Council and the president are elected from and by its Fellows, the basic members of the society, who are themselves elected by existing Fellows. , there are about 1,700 fellows, allowed to use the postnominal title FRS (Fellow of the Royal Society) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monetary Policy
Monetary policy is the policy adopted by the monetary authority of a nation to affect monetary and other financial conditions to accomplish broader objectives like high employment and price stability (normally interpreted as a low and stable rate of inflation). Further purposes of a monetary policy may be to contribute to economic stability or to maintain predictable exchange rates with other currencies. Today most central banks in developed countries conduct their monetary policy within an inflation targeting framework, whereas the monetary policies of most developing countries' central banks target some kind of a fixed exchange rate system. A third monetary policy strategy, targeting the money supply, was widely followed during the 1980s, but has diminished in popularity since then, though it is still the official strategy in a number of emerging economies. The tools of monetary policy vary from central bank to central bank, depending on the country's stage of development, inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotine
Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is used for smoking cessation to relieve drug withdrawal, withdrawal symptoms. Nicotine acts as a receptor agonist at most nicotinic acetylcholine receptors (nAChRs), except at two nicotinic receptor subunits (nAChRα9 and nAChRα10) where it acts as a receptor antagonist. Nicotine constitutes approximately 0.6–3.0% of the dry weight of tobacco. Nicotine is also present at Parts-per notation, ppb concentrations in edible plants in the family Solanaceae, including potatoes, tomatoes, and eggplants, though sources disagree on whether this has any biological significance to human consumers. It functions as an plant defense against herbivory, antiherbivore toxin; consequently, nicotine was widely used as an insecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hippolyte Visart De Bocarmé
Hippolyte Visart de Bocarmé (Weltevreden, Java 14 June 1818 – Mons, Belgium 19 July 1851) was a Belgian nobleman and convicted murderer. He poisoned his brother-in-law in order to acquire some urgently needed money. In 1851, the chemist Jean Servais Stas proved that Visart de Bocarmé had used nicotine extracted from tobacco leaves as poison. This was the first exact proof of alkaloids in forensic medicine. Life Hippolyte Visart de Bocarmé descended from the Belgian noble family Visart de Bocarmé. His father was Julien Visart de Bocarmé (1787–1851) and his mother Ida du Chasteler (1797–1873). His father was a nephew of Johann-Gabriel, Marquess of Chasteler and Courcelles. Visart de Bocarmé was born aboard a ship heading to Java, where his father had signed to serve as vice-governor. His birth certificate was issued in 1819 in Malaysia. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ida Freund
Ida Freund (5 April 1863 – 15 May 1914) was the first woman to be a university chemistry lecturer in the United Kingdom. She is known for her influence on science teaching, particularly the teaching of women and girls. She wrote two key chemistry textbooks and invented the idea of baking periodic table cupcakes, as well as inventing a gas measuring tube, which was named after her. Biography Ida Freund was born in the Austrian Empire. Following the death of her mother, she moved to live with her grandparents in Vienna. In 1881 her grandparents died, and she moved to England to live with her uncle and guardian, the violinist Ludwig Straus well known as a member of the Joachim Quartet and leader of the Hallé Orchestra (1875–88). She enrolled in Girton College, achieving a first class honours in the Natural Sciences Tripos course despite having previously had only school level English language skills. She went on to Cambridge Training College for Women as a chemistry lectu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Morley
Edward Williams Morley (January 29, 1838 – February 24, 1923) was an American scientist known for his precise and accurate measurement of the atomic weight of oxygen, and for the Michelson–Morley experiment. Biography Morley was born in Newark, New Jersey, to Anna Clarissa Treat and the Reverend Sardis Brewster Morley. Both parents were of early colonial ancestry and of purely British origin. He grew up in West Hartford, Connecticut. During his childhood, he suffered much from ill health and was therefore educated by his father at home until the age of nineteen. In 1857 Morley entered Williams College at Williamstown, Massachusetts, his father's alma mater. He received his A.B. in 1860 and his master's degree in 1863. Around 1860 he gradually shifted his attention from chemistry, which fascinated him since he was child, to optics and astronomy. In 1860–61 he mounted a transit instrument, constructed a chronograph, and made the first accurate determination of the latitude o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, energy change as new products are generated. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the Atomic nucleus, nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive Chemical element, elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reagent, reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more Product (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conservation Of Mass
In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter the mass of the system must remain constant over time. The law implies that mass can neither be created nor destroyed, although it may be rearranged in space, or the entities associated with it may be changed in form. For example, in chemical reactions, the mass of the chemical components before the reaction is equal to the mass of the components after the reaction. Thus, during any chemical reaction and low-energy thermodynamic processes in an isolated system, the total mass of the reactants, or starting materials, must be equal to the mass of the products. The concept of mass conservation is widely used in many fields such as chemistry, mechanics, and fluid dynamics. Historically, mass conservation in chemical reactions was primarily demonstrated in the 17th century and finally confirmed by Antoine Lavoisier in the late 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antoine Lavoisier
Antoine-Laurent de Lavoisier ( ; ; 26 August 17438 May 1794), When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air and that it was the air itself "undivided, without alteration, without decomposition" which combined with metals on calcination. After returning from Paris, Priestley took up once again his investigation of the air from mercury calx. His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and ... every other use of common air". He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater ease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dmitri Mendeleev
Dmitri Ivanovich Mendeleev ( ; ) was a Russian chemist known for formulating the periodic law and creating a version of the periodic table of elements. He used the periodic law not only to correct the then-accepted properties of some known elements, such as the valence and atomic weight of uranium, but also to predict the properties of three elements that were yet to be discovered (germanium, gallium and scandium). Early life Mendeleev was born in the village of Verkhnie Aremzyani, near Tobolsk in Siberia, to Ivan Pavlovich Mendeleev (1783–1847) and Maria Dmitrievna Mendeleeva (née Kornilieva) (1793–1850).''Maria Mendeleeva (1951)''. D. I. Mendeleev's Archive: Autobiographical Writings. Collection of Documents. Volume 1 /Biographical notes about D. I. Mendeleev (written by me – D. Mendeleev), p. 13 – Leningrad: D. I. Mendeleev's Museum-Archive, 207 pages (in Russian) Ivan worked as a school principal and a teacher of fine arts, politics and philosophy at the Tambov an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
