scholarly journals Constructing models in teaching of chemical bonds: Ionic bond, covalent bond, double and triple bonds, hydrogen bond and molecular geometry

2015 ◽  
Vol 10 (4) ◽  
pp. 491-500
Author(s):  
Uce Musa
Keyword(s):  
Hydrogen Bond ◽  
Covalent Bond ◽  
Molecular Geometry ◽  
Chemical Bonds ◽  
Ionic Bond ◽  
Triple Bonds

Effect of Ionic Bond in Recording Materials on Characteristics of Phase-Change Optical Disk

2003 ◽  
Vol 803 ◽  
Author(s):  
Motoyasu Terao
Keyword(s):  
Phase Change ◽  
Covalent Bond ◽  
Optical Disk ◽  
Chemical Bonds ◽  
Ionic Bond ◽  
Crystallization Speed ◽  
Ionic Bonds

ABSTRACTThis paper discusses a crystallization model that takes difference of covalent bond and ionic bond into consideration. Ionic bond makes crystallization easier than covalent bond because ionic bond is more flexible than covalent bond. The diameter and spaces around large minus-ions should also be taken into consideration. Elements••having electronic negativity far from that of Te or Sb has a tendency to form ionic bonds. For example, Tb and In are considered to make chemical bonds having more ionic characteristics than Ge. In the case of already reported Sn or Bi addition, large ion diameter seems to increase crystallization speed.

Rietveld refinement of the cocrystal 2,4-dihydroxybenzoic acid–N′-(propan-2-ylidene)nicotinohydrazide (1/1)

2012 ◽  
Vol 68 (9) ◽  
pp. o335-o337 ◽  
Author(s):  
Saul H. Lapidus ◽  
Andreas Lemmerer ◽  
Joel Bernstein ◽  
Peter W. Stephens
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Powder Diffraction ◽  
Supramolecular Assembly ◽  
Covalent Bond ◽  
Analytical Tool ◽  
Powder Diffraction Data ◽  
Dihydroxybenzoic Acid ◽  
Bond Forming ◽  
Hydrogen Bond Interactions

A further example of using a covalent-bond-forming reaction to alter supramolecular assembly by modification of hydrogen-bonding possibilities is presented. This concept was introduced by Lemmerer, Bernstein & Kahlenberg [CrystEngComm(2011),13, 55–59]. The title structure, C9H11N3O·C7H6O4, which consists of a reacted niazid molecule,viz.N′-(propan-2-ylidene)nicotinohydrazide, and 2,4-dihydroxybenzoic acid, was solved from powder diffraction data using simulated annealing. The results further demonstrate the relevance and utility of powder diffraction as an analytical tool in the study of cocrystals and their hydrogen-bond interactions.

Insight into structure, stability and hydrogen bond in complexes of guanine and thymine at the molecular level using computational chemical method

2021 ◽  
Vol 11 (1) ◽  
pp. 127-134
Author(s):  
Nhung Ngo Thi Hong ◽  
Huong Dau Thi Thu ◽  
Trung Nguyen Tien
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Energy Surface ◽  
Covalent Bond ◽  
Electrostatic Energy ◽  
Substantial Contribution ◽  
Structure Stability ◽  
Dispersion Terms ◽  
Insight Into

Nine stable structures of complexes formed by interaction of guanine with thymine were located on potential energy surface at B3LYP/6-311++G(2d,2p). The complexes are quite stable with interaction energy from -5,8 to -17,7 kcal.mol-1. Strength of complexes are contributed by hydrogen bonds, in which a pivotal role of N−H×××O/N overcoming C−H×××O/N hydrogen bond, up to to 3.5 times, determines stabilization of complexes investigated. It is found that polarity of N/C−H covalent bond over proton affinity of N/O site governs stability of hydrogen bond in the complexes. The obtained results show that the N/C−H×××O/N red-shifting hydrogen bonds occur in all complexes, and a larger magnitude of an elongation of N−H compared C-H bond length accompanied by a decrease of its stretching frequency is detected in the N/C−H×××O/N hydrogen bond upon complexation. The SAPT2+ analysis indicates the substantial contribution of attractive electrostatic energy versus the induction and dispersion terms in stabilizing the complexes.

scholarly journals Effect of Doping on the Photoelectric Properties of Borophene

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Chunhong Zhang ◽  
Zhongzheng Zhang ◽  
Wanjun Yan ◽  
Xinmao Qin
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Population Analysis ◽  
Covalent Bond ◽  
Infrared Light ◽  
Chemical Bonds ◽  
Mulliken Population Analysis ◽  
Mulliken Population ◽  
Photoelectric Properties ◽  
Effect Of Doping

Borophene is a new type of two-dimensional material with a series of unique and diversified properties. However, most of the research is still in its infancy and has not been studied in depth. Especially in the field of semiconductor optoelectronics, there is no related research on the modulation of photoelectric properties of borophene. In this work, we focus on the effect of doping on the photoelectric properties of borophene by using the first-principles pseudopotential plane wave method. We calculate the geometric structure, electronic structure, Mulliken population analysis, and optical properties of impurity (X = Al, Ga) doped α-sheet borophene. The results show that α-sheet borophene is an indirect band gap semiconductor with 1.396 eV. The band gap becomes wider after Al and Ga doping, and the band gap values are 1.437 eV and 1.422 eV, respectively. Due to the orbital hybridization between a small number of Al-3p electrons and Ga-4p state electrons and a large number of B 2p state electrons near the Fermi level, the band gap of borophene changes and the peak value of the electron density of states reduces after doping. Mulliken population analysis shows that the B0-B bond is mainly covalent bond, but there is also a small amount of ionic bond. However, when the impurity X is doped, the charge transfer between X and B atoms increases significantly, and the population of the corresponding X-B bonds decreases, indicating that the covalent bond strength of the chemical bonds in the doped system is weakened, and the chemical bonds have significant directionality. The calculation of optical properties shows that the static dielectric constant of the borophene material increases, and the appearance of a new dielectric peak indicates that the doping of Al and Ga can enhance the ability of borophene to store electromagnetic energy. After doping, the peak reflectivity decreases and the static refractive index n0 increases, which also fills the gap in the absorption of red light and infrared light by borophene materials. The research results provide a basis for the development of borophene materials in the field of infrared detection devices. The above results indicate that doping can modulate the photoelectric properties of α-sheet borophene.

scholarly journals Solid polymer electrolyte based on ionic bond or covalent bond functionalized silica nanoparticles

RSC Advances ◽  
2017 ◽  
Vol 7 (87) ◽  
pp. 54986-54994 ◽  
Author(s):  
Ji Hu ◽  
Wanhui Wang ◽  
Ronghua Yu ◽  
Mengke Guo ◽  
Chengen He ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Lithium Ion Batteries ◽  
Polymer Electrolyte ◽  
Solid Polymer Electrolyte ◽  
Covalent Bond ◽  
Lithium Ion ◽  
Solid Polymer ◽  
Functionalized Silica ◽  
Ionic Bond ◽  
Functionalized Silica Nanoparticles

This article reports a solid polymer electrolyte based on ionic bond or covalent bond functionalized silica nanoparticles for lithium ion batteries.

scholarly journals First principle study of occupancy, bonding characteristics and alloying effect of Zr, Nb, V in bulk γ-Fe(C)

2020 ◽  
Vol 213 ◽  
pp. 01019
Author(s):  
Fei Liu ◽  
Shan Cong ◽  
Long Hao
Keyword(s):  
Solid Solution ◽  
Covalent Bond ◽  
Alloy Element ◽  
Chemical Bonds ◽  
Covalent Bonds ◽  
Binding Characteristics ◽  
Crystal Cell ◽  
Ionic Bonds ◽  
Crystal Cells ◽  
Bonding Characteristics

The total energy, binding characteristics, density of states, charge distribution and differential charge density of γ-Fe(C)-M crystal cells formed by solid solution of Zr, Nb and V in γ-Fe(C) were calculated by using the first-principles method. Thus, the mechanism of Zr, Nb, and V with γ-Fe(C) was investigated in this paper. The results show that Zr, Nb and V all preferentially replaced the Fe atoms which are at the top angle in γ-Fe(C). Crystal cell reaches its highest stability after V solid solution. Nb reaches after it, and Zr is relatively weak. In the γ-Fe(C)-Zr cell, Fe-Zr covalent bond and Zr-C ionic bond are the main chemical bonds. In the γ-Fe(C)-Nb and γ-Fe(C)-V cells, Fe-Nb and Fe-V covalent bonds are the main chemical bonds with a number of Nb-C and V-C ionic bonds. After solid solution, the electron cloud density around C atom changed little, while Fe atom changed obviously. The orbital electrons around Fe atoms in γFe(C)-V has maximal distribution, which means that the electrons delocalized most and most of the electrons are bonding. It is the main factor for the increase in the binding energy of crystal cell. The effects of Zr, Nb, V solution on austenitic stability are investigated by studying the influence of alloy element on γFe(C) electronic structure.

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