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Molecular Isobar
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] |
PTCDA AFM
Perylenetetracarboxylic dianhydride (PTCDA) is an organic compound, organic dye molecule and an organic semiconductor. It is used as a precursor to a class of molecules known as Rylene dyes, which are useful as pigments and dyes. It is a dark red solid with low solubility in aromatic solvents. The compound has attracted much interest as an organic semiconductor. Structure PTCDA consists of a perylene core to which two Organic acid anhydride, anhydride groups have been attached, one at either side. It occurs in two crystalline forms, α and β. Both have the P21/c monoclinic symmetry and a density of ca. 1.7 g/cm3, which is relatively high for organic compounds. Their lattice parameters are: Self-assembly and films Use The main industrial use of PTCDA is as a precursor to Rylene dyes.Hunger, K. and Herbst, W. (2012) "Pigments, Organic" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. Greene, M. (2009) "Perylene Pigments", pp. 261–274 in High P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteronuclear
A heteronuclear molecule is a molecule composed of atoms of more than one chemical element. For example, a molecule of water (H2O) is heteronuclear because it has atoms of two different elements, hydrogen (H) and oxygen (O). Similarly, a heteronuclear ion is an ion that contains atoms of more than one chemical element. For example, the carbonate ion () is heteronuclear because it has atoms of carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ... (C) and oxygen (O). The lightest heteronuclear ion is the helium hydride ion (HeH+). This is in contrast to a homonuclear ion, which contains all the same kind of atom, such as the dihydrogen cation, or atomic ions that only contain one atom such as the hydrogen anion (H−). References See also * Homonuclear molecule * Chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linus Pauling
Linus Carl Pauling ( ; February 28, 1901August 19, 1994) was an American chemist and peace activist. He published more than 1,200 papers and books, of which about 850 dealt with scientific topics. ''New Scientist'' called him one of the 20 greatest scientists of all time. For his scientific work, Pauling was awarded the Nobel Prize in Chemistry in 1954. For his peace activism, he was awarded the Nobel Peace Prize in 1962. He is one of five people to have Nobel Prize#Multiple laureates, won more than one Nobel Prize. Of these, he is the only person to have been awarded two unshared Nobel Prizes, and one of two people to be awarded Nobel Prizes in different fields, the other being Marie Curie. Pauling was one of the founders of the fields of quantum chemistry and molecular biology. His contributions to the theory of the chemical bond include the concept of orbital hybridisation and the first accurate scale of electronegativity, electronegativities of the elements. Pauling also wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean Baptiste Perrin
Jean Baptiste Perrin (; 30 September 1870 – 17 April 1942) was a French atomic physicist who, in his studies of the Brownian motion of minute particles suspended in liquids (sedimentation equilibrium), verified Albert Einstein's explanation of this phenomenon and thereby confirmed the atomic nature of matter. For this achievement, he was honoured with the Nobel Prize in Physics in 1926. Biography Early years Born in Lille, France, Perrin attended the École normale supérieure, the elite ''grande école'' in Paris. He became an assistant at the school during the period of 1894–97 when he began the study of cathode rays and X-rays. He was awarded the degree of '' docteur ès sciences'' in 1897. In the same year, he was appointed as a lecturer in physical chemistry at the Sorbonne, Paris. He became a professor at the university in 1910, holding this post until the German occupation of France during World War II. Research and achievements In 1895, Perrin showed that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amedeo Avogadro
Lorenzo Romano Amedeo Carlo Avogadro, Count of Quaregna and Cerreto (, also , ; 9 August 17769 July 1856) was an Italian scientist, most noted for his contribution to molecular theory now known as Avogadro's law, which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. In tribute to him, the ratio of the number of elementary entities (atoms, molecules, ions or other particles) in a substance to its amount of substance (the latter having the unit mole), , is known as the Avogadro constant. This constant is denoted ''N''A, and is one of the seven defining constants of the SI. Biography Amedeo Avogadro was born in Turin to a noble family of the Kingdom of Sardinia (now part of Italy) in the year 1776. He graduated in ecclesiastical law at the late age of 20 and began to practice. Soon after, he dedicated himself to physics and mathematics (then called ''positive philosophy''), and in 1809 starte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Boyle
Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, Alchemy, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of modern chemistry, and one of the pioneers of modern experimental scientific method. He is best known for Boyle's law, which describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system. Among his works, ''The Sceptical Chymist'' is seen as a cornerstone book in the field of chemistry. He was a devout and pious Anglican and is noted for his works in theology. Biography Early years Boyle was born at Lismore Castle in County Waterford, in the far south of Ireland, the seventh son and fourteenth child of Richard Boyle, 1st Earl of Cork, the 1st Earl of Cork ("the Great Earl of Cork") and Catherine Fenton Boyle, Catherine Fenton. Lord Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica
The is a general knowledge, general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. Since 2016, it has been published exclusively as an online encyclopedia, online encyclopaedia. Printed for 244 years, the ''Britannica'' was the longest-running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in Edinburgh, Scotland, in three volumes. The encyclopaedia grew in size; the second edition was 10 volumes, and by its fourth edition (1801–1810), it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent contributors, and the 9th (1875–1889) and Encyclopædia Britannica Eleventh Edition, 11th editions (1911) are landmark encyclopaedias for scholarship and literary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionic Bond
Ionic bonding is a type of chemical bond A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons a ...ing that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding, along with covalent bonding and metallic bonding. Ions are atoms (or groups of atoms) with an electrostatic charge. Atoms that gain electrons make negatively charged ions (called anions). Atoms that lose electrons make positively charged ions (called cations). This transfer of electrons is known as electrovalence in contrast to covalent bond, covalence. In the simplest case, the cation is a metal atom and the anion is a Nonmetal (chemistry), nonmetal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
