Bonding between atoms

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  • Innovation in engineering often means the clever use of a new material - new to a particular application, but not necessarily (although sometimes) new in the sense of ‘recently developed’. Plastic paper clips and ceramic turbine-blades both represent attempts to do better with polymers and ceramics what had previously been done well with metals. And engineering disasters are frequently caused by the misuse of materials.

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  • Molecules, small structures composed of atoms, are essential substances for lives. However, we didn’t have the clear answer to the following questions until the 1920s: why molecules can exist in stable as rigid networks between atoms, and why molecules can change into different types of molecules. The most important event for solving the puzzles is the discovery of the quantum mechanics. Quantum mechanics is the theory for small particles such as electrons and nuclei, and was applied to hydrogen molecule by Heitler and London at 1927.

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  • Two of the main distinctions between chemical engineers and other engineering disciplines are the topics of mass and energy balances. Within these two topics there are a lot of underlying chemical principles that help chemical engineers to perform calculations to determine what is happening in a system, allowing better control of a process.

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  • The complexation of E- and Z-enolborinate E, Z with acetaldehyde R should be proceed via two types: the fisrt, anti-complexation, leading to two types of complexes. The second, syncomplexation, leading only to one type of complexes. In addition, one of two complexes of the anti-complexation have intramolecular hydrogen-bonding between formyl hydrogen on R with oxygen atom on E, Z. The complexes containing intramolecular hydrogen-bonding are the most stables in comparison with the others.

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  • Greek philosopher Empedocles (500 BC) suggested that chemical changes are caused by an emotional likes and dislikes. The love between two substances will make them unite and form a third substance. On the other hand, if the substances start to had each other they will decompose.

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  • In IONIC BONDING the valence electrons are completely transferred from one atom to the other atom. Ionic bonds occur between metals and nonmetals when there is a large difference in electronegativity. In COVALENT BONDING the valence electrons are shared as pairs between the bonded atoms. Pure covalent bonding only occurs when two nonmetal atoms of the same kind bind to each other. When two different nonmetal atoms are bonded or a nonmetal and a metal are bonded, then the bond is a mixture of covalent and ionic bonding called polar covalent bonding.

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  • The structure and dynamics of proteins and enzymatic activity is intrinsically linked to the strength and positions of hydrogen bonds in the system.[1] A hydrogen bond results from an attractive force between an electronegative atom and a hydrogen atom.[2] The hydrogen is attached to a strongly electronegative heteroatom, such as oxygen or nitrogen, termed the hydrogen- bond donor. This electronegative atom decentralizes the electron cloud around the hydrogen nucleus, leaving the hydrogen atom with a positive partial charge.

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  • Drug-Receptor Interaction partial charges. When a hydrogen atom bearing a partial positive charge bridges two atoms bearing a partial negative charge, a hydrogen bond is created. A van der Waals’ bond (B) is formed between apolar molecular groups that have come into close proximity. Spontaneous transient distortion of electron clouds (momentary faint dipole, !!) may induce an opposite dipole in the neighboring molecule. The van der Waals’ bond, therefore, is a form of electrostatic attraction, albeit of very low strength (inversely proportional to the seventh power of the distance).

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  • In the present article, we address the question that how important role do the Quantum Mechanic (QM) and Molecular Mechanics (MM) forces play in ligand docking on protein, via the use semi-quantum relaxation approach (SQRA) using different forces, e.g. quantum, Van der Waals and Coulomb ones, in the process of ligand - protein docking. The QM approximation is applied to calculate the QM forces of neighbor protein-atoms acting on ligands. The L-J 6-12 empirical potential model and Coulomb rule are applied to calculate the forces from the rest protein-atoms on each ligand - atom.

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  • Chapter 2 - The chemical context of life. In this chapter, you should now be able to: Identify the four major elements; distinguish between the following pairs of terms: neutron and proton, atomic number and mass number, atomic weight and mass number; distinguish between and discuss the biological importance of the following: nonpolar covalent bonds, polar covalent bonds, ionic bonds, hydrogen bonds, and van der Waals interactions.

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