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Keith J. Laidler
Keith James Laidler (January 3, 1916 – August 26, 2003), born in England, was notable as a pioneer in chemical kinetics and authority on the physical chemistry of enzymes. Education Laidler received his early education at Liverpool College. He received his BA (1934) and MA (1938) degrees from Oxford University as a student of Trinity College.Keith James Laidler, Physical Chemistry, A pioneer in the field of chemical kinetics and activated-complex theory The science.ca team, GCS Research Society (2001 and 2015).Keith J. Laidle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liverpool
Liverpool is a port City status in the United Kingdom, city and metropolitan borough in Merseyside, England. It is situated on the eastern side of the River Mersey, Mersey Estuary, near the Irish Sea, north-west of London. With a population of (in ), Liverpool is the administrative, cultural and economic centre of the Liverpool City Region, a combined authority, combined authority area with a population of over 1.5 million. Established as a borough in Lancashire in 1207, Liverpool became significant in the late 17th century when the Port of Liverpool was heavily involved in the Atlantic slave trade. The port also imported cotton for the Textile manufacture during the British Industrial Revolution, Lancashire textile mills, and became a major departure point for English and Irish emigrants to North America. Liverpool rose to global economic importance at the forefront of the Industrial Revolution in the 19th century and was home to the Liverpool and Manchester Railway, firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Research Council Of Canada
The National Research Council Canada (NRC; ) is the primary national agency of the Government of Canada dedicated to science and technology research and development. It is the largest federal research and development organization in Canada. The Minister of Innovation, Science, and Economic Development is responsible for the NRC. Mandate NRC is an agency of the Government of Canada, and its mandate is set out in the '' National Research Council Act''. Under the Act, the NRC is responsible for: * Undertaking, assisting or promoting scientific and industrial research in fields of importance to Canada; * Providing vital scientific and technological services to the research and industrial communities; * Investigating standards and methods of measurement; * Working on the standardization and certification of scientific and technical apparatus, instruments and materials used or usable by Canadian industry; * Operating and administering any astronomical observatories established o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical (chemistry)
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: * Electron transfer, Electron-transfer – Only one (usually) electron flows from the atom, ion, or molecule being oxidized to the atom, ion, or molecule that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * Atom transfer – An atom transfers from one Substrate (chemistry), substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously, the oxidation state of oxygen decreases as it accepts electrons r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric
In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they shift, only slightly, from their average equilibrium positions, causing dielectric polarisation. Because of Polarisation density, dielectric polarisation, positive charges are displaced in the direction of the field and negative charges shift in the direction opposite to the field. This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly Chemical bond, bonded molecules, those molecules not only become polarised, but also reorient so that their Symmetry axis, symmetry axes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvation
Solvations describes the interaction of a solvent with dissolved molecules. Both ionized and uncharged molecules interact strongly with a solvent, and the strength and nature of this interaction influence many properties of the solute, including solubility, reactivity, and color, as well as influencing the properties of the solvent such as its viscosity and density. If the attractive forces between the solvent and solute particles are greater than the attractive forces holding the solute particles together, the solvent particles pull the solute particles apart and surround them. The surrounded solute particles then move away from the solid solute and out into the solution. Ions are surrounded by a concentric shell of solvent. Solvation is the process of reorganizing solvent and solute molecules into solvation complexes and involves bond formation, hydrogen bonding, and van der Waals forces. Solvation of a solute by water is called hydration. Solubility of solid compounds dep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solution (chemistry)
In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. When, as is often but not necessarily the case, the sum of the mole fractions of solutes is small compared with unity, the solution is called a dilute solution. A superscript attached to the ∞ symbol for a property of a solution denotes the property in the limit of infinite dilution." One important parameter of a solution is the concentration, which is a measure of the amount of solute in a given amount of solution or solvent. The term " aqueous solution" is used when one of the solvents is water. Types ''Homogeneous'' means that the components of the mixture form a single phase. ''Heterogeneous'' means that the components of the mixture are of different phase. The properties of the mixture (such as concentration, temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactions On Surfaces
Reactions on surfaces are reactions in which at least one of the steps of the reaction mechanism is the adsorption of one or more reactants. The mechanisms for these reactions, and the rate equations are of extreme importance for heterogeneous catalysis. Via scanning tunneling microscopy, it is possible to observe reactions at the solid gas interface in real space, if the time scale of the reaction is in the correct range. Reactions at the solid–gas interface are in some cases related to catalysis. Simple decomposition If a reaction occurs through these steps: : A + S ⇌ AS → Products where A is the reactant and S is an adsorption site on the surface and the respective rate constants for the adsorption, desorption and reaction are ''k''1, ''k''−1 and ''k''2, then the global reaction rate is: :r=k_2 C_\mathrm=k_2 \theta C_\mathrm where: * ''r'' is the rate, mol·''m''−2·s−1 * C_A is the concentration of adsorbate, ''mol·m−3'' * C_\mathrm is the surface co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction. The detailed steps of a reaction are not observable in most cases. The conjectured mechanism is chosen because it is thermodynamically feasible and has experimental support in isolated intermediates (see next section) or other quantitative and qualitative characteristics of the reaction. It also describes each reactive intermediate, activated complex, and transition state, which bonds are broken (and in what order), and which bonds are formed (and in what order). A complete mechanism must also explain the reason for the reactants and catalyst used, the stereochemistry observed in reactants and products, all products formed and the amount of each. The electron or arrow pushing method is often used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potential Energy Surface
A potential energy surface (PES) or energy landscape describes the energy of a Physical system, system, especially a collection of atoms, in terms of certain Parameter, parameters, normally the positions of the atoms. The Surface (mathematics), surface might define the energy as a Function (mathematics), function of one or more coordinates; if there is only one coordinate, the surface is called a ''potential energy curve'' or energy profile. An example is the Morse/Long-range potential. It is helpful to use the analogy of a landscape: for a system with two Degrees of freedom (physics and chemistry), degrees of freedom (e.g. two bond lengths), the value of the energy (analogy: the height of the land) is a function of two bond lengths (analogy: the coordinates of the position on the ground). The PES concept finds application in fields such as physics, chemistry and biochemistry, especially in the theoretical sub-branches of these subjects. It can be used to theoretically explore p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excited State
In quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ..., an excited state of a system (such as an atom, molecule or Atomic nucleus, nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). Excitation refers to an increase in energy level above a chosen starting point, usually the ground state, but sometimes an already excited state. The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit negative temperature). The lifetime of a system in an excited state is usually short: Spontaneous emission, spontaneous or stimulated emission, induced emission of a quantum of energy (such as a photon or a phonon) usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactivity (chemistry)
In chemistry, reactivity is the impulse for which a chemical substance undergoes a chemical reaction, either by itself or with other materials, with an overall release of energy. ''Reactivity'' refers to: * the chemical reactions of a single substance, * the chemical reactions of two or more substances that interact with each other, * the systematic study of sets of reactions of these two kinds, * methodology that applies to the study of reactivity of chemicals of all kinds, * experimental methods that are used to observe these processes, and * theories to predict and to account for these processes. The chemical reactivity of a single substance (reactant) covers its behavior in which it: * decomposes, * forms new substances by addition of atoms from another reactant or reactants, and * interacts with two or more other reactants to form two or more products. The chemical reactivity of a substance can refer to the variety of circumstances (conditions that include temperature, pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
