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Structural Theory
In chemistry, structural theory explains the large variety in chemical compounds in terms of atoms making up molecules, the arrangement of atoms within molecules and the electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...s that hold them together. According to structural theory, from the structural formula of a molecule it is possible to derive physical and spectroscopic data and to predict chemical reactivity. Beginning from about 1858, many scientists from several countries took part in the early development of structural theory, including August Kekule, Archibald Scott Couper, and Aleksandr Mikhailovich Butlerov. It was Butlerov who coined the phrase "chemical structure" in the following quotation from an article published in 1861: …the chemical nature of a compou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
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 chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions with other chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken or new bonds formed or both. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, usin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atom
Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics is not possible due to quantum mechanics, quantum effects. More than 99.94% of an atom's mass is in the nucleus. Protons hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecule
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (molecule), water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up quark, up and down quark, down quarks. Electrons are extremely lightweight particles that orbit the positively charged atomic nucleus, nucleus of atoms. Their negative charge is balanced by the positive charge of protons in the nucleus, giving atoms their overall electric charge#Charge neutrality, neutral charge. Ordinary matter is composed of atoms, each consisting of a positively charged nucleus surrounded by a number of orbiting electrons equal to the number of protons. The configuration and energy levels of these orbiting electrons determine the chemical properties of an atom. Electrons are bound to the nucleus to different degrees. The outermost or valence electron, valence electrons are the least tightly bound and are responsible for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Formula
The structural formula of a chemical compound is a graphic representation of the molecular structure (determined by structural chemistry methods), showing how the atoms are connected to one another. The chemical bonding within the molecule is also shown, either explicitly or implicitly. Unlike other chemical formula types, which have a limited number of symbols and are capable of only limited descriptive power, structural formulas provide a more complete geometric representation of the molecular structure. For example, many chemical compounds exist in different isomeric forms, which have different enantiomeric structures but the same molecular formula. There are multiple types of ways to draw these structural formulas such as: Lewis structures, condensed formulas, skeletal formulas, Newman projections, Cyclohexane conformations, Haworth projections, and Fischer projections. Several systematic chemical naming formats, as in chemical databases, are used that are equivalent to, an ... [...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] |
August Kekule
August is the eighth month of the year in the Julian and Gregorian calendars. Its length is 31 days. In the Southern Hemisphere, August is the seasonal equivalent of February in the Northern Hemisphere. In the Northern Hemisphere, August falls in summer. In the Southern Hemisphere, the month falls during winter. In many European countries, August is the holiday month for most workers. Numerous religious holidays occurred during August in ancient Rome. Certain meteor showers take place in August. The Kappa Cygnids occur in August, with yearly dates varying. The Alpha Capricornids meteor shower occurs as early as July 10 and ends around August 10. The Southern Delta Aquariids occur from mid-July to mid-August, with the peak usually around July 28–29. The Perseids, a major meteor shower, typically takes place between July 17 and August 24, with the peak days varying yearly. The star cluster of Messier 30 is best observed around August. Among the aborigines of the Canary I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archibald Scott Couper
Archibald Scott Couper (; 31 March 1831 – 11 March 1892) was a Scottish chemist who proposed an early theory of chemical structure and bonding. He developed the concepts of tetravalent carbon atoms linking together to form large molecules, and that the bonding order of the atoms in a molecule can be determined from chemical evidence. Life and work Couper was the only surviving son of a wealthy textile mill owner near Glasgow. He studied at the universities of Glasgow and Edinburgh and intermittently in Germany during the years 1851-54. He began the formal study of chemistry at the University of Berlin in the autumn of 1854, then in 1856 entered Charles Adolphe Wurtz's private laboratory at the Faculty of Medicine in Paris (now the University of Paris V: René Descartes). Couper published his "New Chemical Theory" in French in a condensed form on 14 June 1858, then in detailed papers simultaneously in French and English in August 1858. Couper's idea that carbon atoms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aleksandr Mikhailovich Butlerov
Alexander Mikhaylovich Butlerov (; 15 September 1828 – 17 August 1886) was a Russian chemist, one of the principal creators of the theory of chemical structure (1857–1861), the first to incorporate double bonds into structural formulas, the discoverer of hexamine (1859), the discoverer of formaldehyde (1859) and the discoverer of the formose reaction (1861). He first proposed the idea of possible tetrahedral arrangement of valence bonds in carbon compounds in 1862. The crater Butlerov on the Moon is named after him. In 1956 the Academy of Sciences of the USSR established the A. M. Butlerov Prize. Biography Butlerov was born into a landowning family. In 1849 he graduated from the Imperial Kazan University. after which he worked there as a teacher. From 1860 to 1863 he was the rector. From 1868 to 1885 he was a professor of Chemistry at the Imperial St. Petersburg University. Butlerov was the chairman of the Chemistry Department of the Russian Physico-Chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
