scholarly journals The concepts of an atom and chemical bond in physics and chemistry: the role of approximations

2011 ◽  
Vol 10 (0) ◽  
pp. 31
Author(s):  
Andrzej Koleżyński
Keyword(s):  
Chemical Bond

scholarly journals Leading Interaction Components in the Structure and Reactivity of Noble Gases Compounds

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2367
Author(s):  
Francesca Nunzi ◽  
Giacomo Pannacci ◽  
Francesco Tarantelli ◽  
Leonardo Belpassi ◽  
David Cappelletti ◽  
...  
Keyword(s):  
Chemical Bond ◽  
Theoretical Approach ◽  
Noble Gases ◽  
Halogen Bond ◽  
Noble Gas ◽  
Anomalous Behavior ◽  
Type Interaction ◽  
Long Life ◽  
Weak Chemical

The nature, strength, range and role of the bonds in adducts of noble gas atoms with both neutral and ionic partners have been investigated by exploiting a fine-tuned integrated phenomenological–theoretical approach. The identification of the leading interaction components in the noble gases adducts and their modeling allows the encompassing of the transitions from pure noncovalent to covalent bound aggregates and to rationalize the anomalous behavior (deviations from noncovalent type interaction) pointed out in peculiar cases. Selected adducts affected by a weak chemical bond, as those promoting the formation of the intermolecular halogen bond, are also properly rationalized. The behavior of noble gas atoms excited in their long-life metastable states, showing a strongly enhanced reactivity, has been also enclosed in the present investigation.

scholarly journals Understanding the role of phase in chemical bond breaking with coincidence angular streaking

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
J. Wu ◽  
M. Magrakvelidze ◽  
L.P.H. Schmidt ◽  
M. Kunitski ◽  
T. Pfeifer ◽  
...  
Keyword(s):  
Chemical Bond ◽  
Bond Breaking

scholarly journals ADSORPTION AS A BASIS OF PROTECTIVE ACTION OF FILTERS-ADSORBER

2018 ◽  
Vol 1 (2) ◽  
pp. 59-63
Author(s):  
V Kovalenko ◽  
A Borysova ◽  
I Pliuta ◽  
R Likhnovsky
Keyword(s):  
Adsorption Isotherm ◽  
Chemical Bond ◽  
Metal Ion ◽  
Protective Action ◽  
Chemical Substance ◽  
Hazardous Chemical ◽  
Action Time ◽  
Bet Theory

This article analyzes the regulatory documents on determination of protective action time of gas filters and FILTERS-ADSORBER, which are designed for individual and collective protection. The current absence of a current regulatory document in Ukraine is indicated according to which protective action time of filters is determined, adds relevance in the implementation of the method of determining this filter characteristic. The theoretical aspects of effect of absorbing capacity of filters are highlighted, the fundamental principles of adsorption are linked with the time of protective action time of filters against hazardous chemicals. The process of adsorption on the surface and formation of sorption layers in case of polymolecular adsorption is schematically shown, as described by the BET theory. It is indicated that protective action time on the direct depends on particular case of adsorption - chemisorption. The types of adsorption isotherms are considered, they are characterized and the Langmuir and BET equations are given. The protective action of filter as a phenomena of chemisorption on the surface of sorbent is described by the Langmuir isotherm, in particular, parts I and II. When determining protective action time the monomolecular adsorption of hazardous chemical substance occurs with formation of a chemical bond with the surface. The chemical bond is formed from the impregnated catalyst due to the redistribution of electrons. Solutions of metal salts are used as a catalyst, and the metal ion itself acts as an active center during the process of chemisorption. The role of adsorption kinetics in the implementation of sanitary cleaning of gas from the pollutant in the practical plane is considered. The possibility of calculating the amount of a chemical that a sorbent can absorb is shown by constructing an adsorption isotherm of a standard substance and a pollutant adsorption working line. Adsorption isotherm was captured for adsorbent from FG-130 FPK 95 filter on KELVIN 1042 sorptometr.

scholarly journals Clarifying the quantum mechanical origin of the covalent chemical bond

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel S. Levine ◽  
Martin Head-Gordon
Keyword(s):  
Kinetic Energy ◽  
Chemical Bond ◽  
Quantum Interference ◽  
Bond Formation ◽  
Quantum Mechanical ◽  
Core Electrons ◽  
Pauli Repulsion ◽  
Primary Origin ◽  
Covalent Chemical Bond

Abstract Lowering of the electron kinetic energy (KE) upon initial encounter of radical fragments has long been cited as the primary origin of the covalent chemical bond based on Ruedenberg’s pioneering analysis of H$${}_{2}^{+}$$ 2 + and H2 and presumed generalization to other bonds. This work reports KE changes during the initial encounter corresponding to bond formation for a range of different bonds; the results demand a re-evaluation of the role of the KE. Bonds between heavier elements, such as H3C–CH3, F–F, H3C–OH, H3C–SiH3, and F–SiF3 behave in the opposite way to H$${}_{2}^{+}$$ 2 + and H2, with KE often increasing on bringing radical fragments together (though the total energy change is substantially stabilizing). The origin of this difference is Pauli repulsion between the electrons forming the bond and core electrons. These results highlight the fundamental role of constructive quantum interference (or resonance) as the origin of chemical bonding. Differences between the interfering states distinguish one type of bond from another.

Phase-change mechanism and role of each element in Ag-In-Sb-Te: Chemical bond evolution

2021 ◽  
Vol 544 ◽  
pp. 148838
Author(s):  
Dasol Kim ◽  
Taek Sun Jung ◽  
Hanjin Park ◽  
Wonjun Yang ◽  
Jeonghwa Han ◽  
...  
Keyword(s):  
Phase Change ◽  
Chemical Bond ◽  
Change Mechanism
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