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Introduction
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
Individual atoms are, in general, highly reactive and unstable, and so they tend to gather into groups known as molecules which lead to the formation of compounds. Compounds have chemical behaviors and physical properties that are distinct from the behavior of their component atoms. For example, ordinary table salt or sodium chloride has nothing in common with either sodium or chlorine, each of which is composed of a highly hazardous, reactive atom. Compounds are generally composed of simple whole number ratios of atoms combined into a new unit. The ways atoms form compounds can be broadly split into two categories, those being through covalent bonding, to make molecules where bonding electrons are shared, or ionic bonding, to make ionic compounds where electrons are effectively transferred from one atom to another. Other types of bonding and materials do exist, such as metallic bonding, necessary for the conduction of electrons in pure metals) and covalent network materials, (e.g. graphene and/or semi-conductors) but most of the concerns here will be covered by molecular and ionic compounds.
Friction on an Atomic Scale
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Jaime Colchero, Ernst Meyer, Othmar Marti
Due to this structure, boundary lubricants can be synthesized in an almost infinite variety: the chain length and its bond character can be varied as well as the head group. Each compound may have distinct physical and chemical properties. Accordingly, one of the aims of boundary lubrication research is to characterize the physical and chemical properties that improve lubrication and wear resistance in order to design and optimize technically relevant boundary lubricants. Typical self-assembling monolayers are thiols (—SH end group), which bind chemically to gold, and silanes (—SiR3 end groups). Very common LB films are Cd—arachidate films, which are a well-established standard for boundary lubrication.
Energy, atoms, and neutrons
Published in Kenneth Jay, Nuclear Power, 2019
Atoms combine with one another to form chemical compounds. The process of combination is called a chemical reaction and it comes about by rearrangement of the outer electrons of the atoms taking part. In the burning of coal, for example, atoms of carbon (which form the chief part of coal) combine with atoms of oxygen from the air, sharing outer electrons, to form carbon dioxide; in the process energy is released in the form of heat and thus triggers off similar combinations among neighbouring atoms and so causes the reaction to spread. The nuclei of the combining atoms are unaffected; the atoms retain their chemical identity.
Good Names but Better Symbols: The Establishment of Chemical Notation as a Nomenclatural Corrective at the Turn of the Nineteenth Century
Published in Ambix, 2021
Guyton et al. believed that a good description of a compound’s composition, one that could sufficiently distinguish it from other compounds, foremost entailed an indication of the compound’s constituent substances. To represent such information in their new names for compounds, they combined the names (or the roots of the names) for the compounds’ constituent substances. For example, the roots of the new name oxide of iron, which replaced the older name saffron of Mars, indicated that the compound consisted of iron and oxygen (oxy-), while carbonated hydrogen gas identified a compound of carbon and hydrogen.15
Synthesis, quantum chemical calculations and molecular docking studies of 2-ethoxy-4[(2-trifluromethyl-phenylimino)methyl]phenol
Published in Molecular Physics, 2020
Towseef Ahmad Hajam, H. Saleem, M. Syed Ali Padhusha, K. K. Mohammed Ameen
Schiff based compounds carry imine or azomethine (–C=N–) functional group. The Schiff based compounds were first reported by Hugo Schiff [1–3]. They are known to form an important class of organic compounds which have broad variety of applications in various fields including analytical, biological and inorganic chemistry. They play a key role in medicinal and pharmaceutical fields due to their broad spectrum of biological activities like anti-inflammatory [4–7], analgesic [5–8], anti-microbial [9,10], anti-convulsant [11], anti-tubercular [12], anti-cancer [13,14], anti-bacterial [15], anthelmintic [16], anti-tumor [17], etc.
Role of surface catalyzed reaction in the flow of temperature-dependent viscosity fluid over a rotating disk
Published in Numerical Heat Transfer, Part A: Applications, 2023
Khalid Abdulkhaliq M Alharbi, Saima Riasat, Muhammad Ramzan, Seifedine Kadry
A chemical reaction is a process that results in the translation of one set of chemical substances into another. During a chemical reaction, bonds between atoms are broken and new bonds are shaped, resulting in new chemical compounds. The substances that react are called reactants, and the substances that are formed as a result of the reaction are called products. A catalyst is a substance that accelerates the rate of a chemical reaction without being expended by the reaction. Catalysts work by providing a substitute trail for the reaction to occur that has a lower activation energy, which is the least amount of energy required for the reaction to proceed. This means that the catalyst helps the reactants to overcome the energy barrier that is necessary for the reaction to occur. As a result, the reactants are able to react more quickly and efficiently in the presence of a catalyst. Catalysts are used in a wide variety of chemical reactions, including those that occur in the industry, in the environment, and in living organisms. Catalysts can be either homogeneous or heterogeneous. Homogeneous catalysts are soluble in the reaction mixture and are present in the same phase as the reactants. Heterogeneous catalysts, on the other hand, are insoluble in the reaction mixture and are present in a different phase. There are many different types of catalysts that can be used to accelerate chemical reactions. Some examples include enzymes (biological catalysts found in living organisms), precious metals (such as platinum and palladium), and various types of solid catalysts (such as zeolites and metal oxides). The use of catalysts is important in many industrial processes, as they can help to increase the efficiency and yield of chemical reactions. Catalysts can also be used to reduce the energy required for a reaction to occur, which can help to reduce greenhouse gas emissions and other environmental impacts. Researchers have shown keen interest in numerous fluid problems involving chemical reactions. Hamid et al. [26] investigated the homogeneous and heterogeneous reaction for hybrid nanofluids by incorporating the Hall effect. Shankaralingappa et al. [27] examined non-Newtonian fluid flow over an elongated sheet with thermophoretic particle deposition. Ramesh et al. [28] deliberated on the activation energy in a chemical reaction. Hayat et al. [29] deliberated the nanofluid flow considering the homogeneous-heterogeneous reactions. Hashmi et al. [30] explored the impact of homogeneous-heterogeneous reactions by using magnetized Maxwell fluid. Riasat et al. [31] studied the impact of magnetic Reynolds numbers along with homogeneous-heterogeneous reactions. Various studies concerning the chemical reaction may be found in Refs. [32–36].