Covalent Radii and New Applications

2018 ◽  
Vol 7 (1) ◽  
pp. 42-51
Author(s):  
Yonghe Zhang
Keyword(s):  
Chemical Reactions ◽  
Data Reduction ◽  
Covalent Radius ◽  
Chemical Bonds ◽  
Atomic Orbitals ◽  
Atomic Property ◽  
Energy Part ◽  
Unique Parameter ◽  
New Applications ◽  
Ionic Energy

Ionocovalency theory is defined “…everything exists in ionocovalency, the harmony of ionic energy with the covalent environment.” The authors have succeeded in thoroughly studying ionic energy part of the ionocovalent theory, and will now focus target on the covalent environment part of the theory. The essence of chemical reactions and chemical bonds is the overlap of atomic orbitals, the electron density or the ionocovalent potential. The covalent radius rc is the unique parameter that can be considered as an atomic property derived from molecules for data reduction and can be assigned to the atoms interacting in molecules. In the present study, A new application view of covalent radii of multidimensional world is revealed by the ionocovalency theory which can quantitatively describe the chemical phenomena and qualitatively correlates to the universal observations.

scholarly journals The Principle of Conservation of Structural Aspect: Facilitating Visual Communication and Learning in Organic Chemistry Instruction

2019 ◽  
Author(s):  
john andraos
Keyword(s):  
Organic Chemistry ◽  
Chemical Reactions ◽  
Reaction Mechanisms ◽  
Visual Communication ◽  
Structural Aspect ◽  
Chemical Bonds ◽  
Journal Articles ◽  
Chemistry Instruction ◽  
Individual Reaction ◽  
Training Exercises

<p>An effective pedagogical method is presented for the visual communication of chemical reactions learned in organic chemistry undergraduate courses. The basis for the method is the preservation of the visual aspect of reactant and product structures so that the tracking of cleaved and formed chemical bonds is made self-evident. This consequently leads to improved clarity of presentation and a better understanding and grasp of proposed reaction mechanisms to explain product outcomes. The method is demonstrated for a variety of individual reaction types and synthesis plans. Various visual training exercises are also presented using ChemDraw Ultra 7.0 software and literature table of contents (TOC) graphics appearing in journal articles.</p><br>

From Atomic Orbitals to Molecular Orbitals and Chemical Bonds

2020 ◽  
pp. 150-187
Author(s):  
Jochen Autschbach
Keyword(s):  
Hydrogen Molecule ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Basis Set ◽  
Orbital Method ◽  
Chemical Bonds ◽  
Atomic Orbitals ◽  
Hartree Fock ◽  
Generalized Matrix

It is shown how an aufbau principle for atoms arises from the Hartree-Fock (HF) treatment with increasing numbers of electrons. The Slater screening rules are introduced. The HF equations for general molecules are not separable in the spatial variables. This requires another approximation, such as the linear combination of atomic orbitals (LCAO) molecular orbital method. The orbitals of molecules are represented in a basis set of known functions, for example atomic orbital (AO)-like functions or plane waves. The HF equation then becomes a generalized matrix pseudo-eigenvalue problem. Solutions are obtained for the hydrogen molecule ion and H2 with a minimal AO basis. The Slater rule for 1s shells is rationalized via the optimal exponent in a minimal 1s basis. The nature of the chemical bond, and specifically the role of the kinetic energy in covalent bonding, are discussed in details with the example of the hydrogen molecule ion.

Chemical Bonds and Their Transformations in the Course of Chemical Reactions

1992 ◽  
Vol 57 (6) ◽  
pp. 1177-1185
Author(s):  
Robert Ponec ◽  
Martin Strnad
Keyword(s):  
Chemical Bond ◽  
Structural Transformation ◽  
Chemical Reactions ◽  
Theoretical Description ◽  
Charge Fluctuation ◽  
Chemical Bonds ◽  
Pericyclic Reactions ◽  
Charge Fluctuations ◽  
Small Charge ◽  
Classical Picture

The Julg's concept of chemical bond as a region of small charge fluctuation was generalized by incorporating into the framework of recently proposed overlap determinant method. The resulting generalization allowing a simple theoretical description of structural transformation in terms close to classical picture of disappearing and newly formed chemical bonds was applied to the analysis of several selected pericyclic reactions both allowed and forbidden. The forbidden reactions were shown to be accompanied by deeper charge fluctuations than the allowed ones.

CHEMICAL REACTIONS IN ELECTRICAL DISCHARGES: I. THE SPECTRUM OF THE METHANE–OXYGEN SYSTEM AT LOW PRESSURE IN THE POSITIVE COLUMN OF A D-C. GLOW DISCHARGE

1964 ◽  
Vol 42 (8) ◽  
pp. 1792-1810
Author(s):  
Pierre A. Bois D'enghien ◽  
Jacques M. Deckers
Keyword(s):  
Carbon Monoxide ◽  
Steady State ◽  
Glow Discharge ◽  
Chemical Reactions ◽  
Positive Column ◽  
Quantitative Relationship ◽  
Chemical Bonds ◽  
Mechanism Of Formation ◽  
Electrical Discharges ◽  
Oxygen System

A technique is described which permits the study of changes in the spectra emitted by fast flowing reacting gas mixtures in the plasma of the positive column of a weak d-c. glow discharge. In certain cases a quantitative relationship is shown to exist between the concentration of a species and the intensity of emission of its spectrum. In particular such a correlation exists between the emission intensity of CO and its concentration. Use of this fact is then made to follow the rate of formation of carbon monoxide in methane–oxygen mixtures flowing through a discharge. The mechanism of formation of the various emitters either by means of a chemical reaction or by electron impact on molecules or radicals is discussed. It is concluded that to account for the rate of formation of CO, at least in the early stages of the presence of the gases in the discharge, before the steady state concentrations of atoms, radicals, and molecules have been approached, most of the energy of the electrons is used in breaking chemical bonds. The electric Held values needed to impart the necessary amount of energy to the electrons are of the same magnitude as those measured in this laboratory (~60 V cm−1).

Role of core and valence atomic orbitals in the formation of chemical bonds

1987 ◽  
Vol 22 (5) ◽  
pp. 544-550 ◽  
Author(s):  
G. P. Kostikova ◽  
Yu. P. Kostikov ◽  
D. V. Korol'kov
Keyword(s):  
Chemical Bonds ◽  
Atomic Orbitals

Life and Its Chemical Foundations

2019 ◽  
pp. 19-55
Keyword(s):  
Chemical Reactions ◽  
Chemical Bonds ◽  
Complex Molecules ◽  
Minor Elements ◽  
Large Complex ◽  
Metabolic Reactions ◽  
Living Organisms ◽  
Life On Earth ◽  
Long Chains

This chapter focuses on the chemical foundations of life. Matter is made up of elements classified into major and minor elements. Elements are made up of atoms which in turn are made up of sub-atomic particles called protons, electrons and neutrons. Chemical bonds are unions of electron structures when atoms lose, gain or share one or more electrons with other atoms. Water is important to life and has unique properties making it ideal to life on Earth. The pH of a substance is a measure of the balance between H+ and OH- ions ranging from 0 to 14 on a log scale. Most metabolic reactions that maintain life occur in living organisms involve five types of chemical reactions. Macromolecules are large complex molecules made up of repeating units (monomers) of sometimes the same molecule or of different molecules joined together by chemical bonds to form very long chains (polymers).

The Principle of Conservation of Structural Aspect: Facilitating Visual Communication and Learning in Organic Chemistry Instruction

2019 ◽  
Author(s):  
john andraos
Keyword(s):  
Organic Chemistry ◽  
Chemical Reactions ◽  
Reaction Mechanisms ◽  
Visual Communication ◽  
Structural Aspect ◽  
Chemical Bonds ◽  
Journal Articles ◽  
Chemistry Instruction ◽  
Individual Reaction ◽  
Training Exercises

<p>An effective pedagogical method is presented for the visual communication of chemical reactions learned in organic chemistry undergraduate courses. The basis for the method is the preservation of the visual aspect of reactant and product structures so that the tracking of cleaved and formed chemical bonds is made self-evident. This consequently leads to improved clarity of presentation and a better understanding and grasp of proposed reaction mechanisms to explain product outcomes. The method is demonstrated for a variety of individual reaction types and synthesis plans. Various visual training exercises are also presented using ChemDraw Ultra 7.0 software and literature table of contents (TOC) graphics appearing in journal articles.</p><br>

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