Chemical bonding across the periodic table

2007 ◽  
pp. 47-166 ◽  
Author(s):  
Nicolaos D. Epiotis
Keyword(s):  
Chemical Bonding ◽  
Periodic Table

POTENTIAL UNUSUAL CHEMICAL BONDING IN MIXED METAL STRUCTURES OF THE 3d TRANSITION SERIES CONTAINING THE ELEMENT Ni

2007 ◽  
Vol 06 (01) ◽  
pp. 165-175
Author(s):  
MICHAEL J. BUCKNUM ◽  
EDUARDO A. CASTRO
Keyword(s):  
Transition Metal ◽  
Chemical Bonding ◽  
Periodic Table ◽  
Three Dimensional ◽  
Metal Structures ◽  
Atomic Orbitals ◽  
Mixed Metal ◽  
Transition Series ◽  
Cscl Structure ◽  
Made In

A heuristic proposal is made in this communication that involves potentially unusual chemical bonding between the 3d transition series element Ni and the 3d transition series metals preceding it in the Periodic Table. The bonding in such mixed metal dimers, and their potential realizations as some simple three-dimensional (3D) extended structures in a one-to-one stoichiometry, as sphaelerite, rocksalt or CsCl structure-types, is proposed to include two principal components that involve either covalent or ionic contributions. Ordinary covalent contributions from a σ bond (or band) formed from overlap of singly occupied 4s atomic orbitals on each metal center are proposed to be operative in these molecules (or their extended realizations). However, in addition to this 4s–4s σ bond (band), an unprecedented transfer of a d electron from the incomplete, open 3d9 subshell of the transition metal involved in the bonding that precedes Ni in the Periodic Table, into the 3d9 subshell on the Ni center, which results in completion of this 3d subshell in Ni , is here implicated as a further driving force for the formation of these species. The resulting molecular and extended structures MNi , where M is a 3d transition metal preceding Ni in the Periodic Table (i.e. M = Sc , Ti , V , Cr , Mn , Fe and Co ), are therefore proposed to be bonded together by a combination of covalent and ionic forces, such that the Ni center acts as an anion of charge 1-, a so-called nickelide anion Ni -, while its counterpart is a univalent cation M +. This proposal is consistent with commonly employed electronegativity scales of chemical bonding, and with considerations of the relative orbital energies of the 3d subshells of the elements across the 3d transition series period, as well as with known trends in covalent and ionic bonding in the Periodic Table of the elements. It is also found to be in agreement with the spin multiplicities calculated in the nickel dimers MNi ( M = Sc , Ti , V , Cr , Mn , Fe and Co ) if Hund's rule is assumed to be operative.

Radiation-induced surface decomposition

1983 ◽  
Vol 41 ◽  
pp. 368-369
Author(s):  
M. L. Knotek
Keyword(s):  
Ionizing Radiation ◽  
Atomic Structure ◽  
Chemical Bonding ◽  
Neutral Species ◽  
Radiation Induced ◽  
Physical And Chemical ◽  
Surface Decomposition ◽  
The Relationship ◽  
Electron And Photon ◽  
Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

Multislice calculations for quasi-periodic and non-periodic objects

1990 ◽  
Vol 48 (4) ◽  
pp. 138-139
Author(s):  
R. Herrera ◽  
A. Gómez
Keyword(s):  
Electron Diffraction ◽  
Computer Simulations ◽  
Periodic Table ◽  
Amorphous Materials ◽  
Space Group ◽  
Essential Step ◽  
Shape Effects ◽  
Atomic Scattering ◽  
Diffraction Patterns ◽  
Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

A Well-Ordered Thing

2018 ◽  
Author(s):  
Michael D. Gordin
Keyword(s):  
Nineteenth Century ◽  
History Of Science ◽  
Periodic Table ◽  
The Arctic ◽  
Classic Work ◽  
Hot Air ◽  
History Of ◽  
First Time

Dmitrii Mendeleev (1834–1907) is a name we recognize, but perhaps only as the creator of the periodic table of elements. Generally, little else has been known about him. This book is an authoritative biography of Mendeleev that draws a multifaceted portrait of his life for the first time. As the book reveals, Mendeleev was not only a luminary in the history of science, he was also an astonishingly wide-ranging political and cultural figure. From his attack on Spiritualism to his failed voyage to the Arctic and his near-mythical hot-air balloon trip, this is the story of an extraordinary maverick. The ideals that shaped his work outside science also led Mendeleev to order the elements and, eventually, to engineer one of the most fascinating scientific developments of the nineteenth century. This book is a classic work that tells the story of one of the world's most important minds.

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