UkrReferat.com
найбільша колекція україномовних рефератів

Всього в базі: 75843
останнє поновлення: 2016-12-04
за 7 днів додано 15

Реферати на українській
Реферати на російській
Українські підручники

$ Робота на замовлення
Реклама на сайті
Зворотній зв'язок

 

ПОШУК:   

реферати, курсові, дипломні:

Українські рефератиРусские рефератыКниги
НазваOn the problem of crystal metallic lattice in the densest packings of chemical elements (реферат)
Автор
РозділІноземна мова, реферати англійською, німецькою
ФорматWord Doc
Тип документуРеферат
Продивилось974
Скачало106
Опис
ЗАКАЧКА
Замовити оригінальну роботу

ON THE PROBLEM OF CRYSTAL METALLIC LATTICE IN THE DENSEST PACKINGS OF

CHEMICAL ELEMENTS

 

G.G FILIPENKO

 

Grodno

 

Abstract

 

The literature generally describes a metallic bond as the one formed by

means of mutual bonds between atoms' exterior electrons and not

possessing the directional properties. However, attempts have been made

to explain directional metallic bonds, as a specific crystal metallic

lattice.

 

This paper demonstrates that the metallic bond in the densest packings

(volume-centered and face-centered) between the centrally elected atom

and its neighbours in general is, probably, effected by 9 (nine)

directional bonds, as opposed to the number of neighbours which equals

12 (twelve) (coordination number).

 

Probably, 3 (three) "foreign" atoms are present in the coordination

number 12 stereometrically, and not for the reason of bond. This problem

is to be solved experimentally.

 

Introduction

 

At present, it is impossible, as a general case, to derive by means of

quantum-mechanical calculations the crystalline structure of metal in

relation to electronic structure of the atom. However, Hanzhorn and

Dellinger indicated a possible relation between the presence of a

cubical volume-centered lattice in subgroups of titanium, vanadium,

chrome and availability in these metals of valent d-orbitals. It is easy

to notice that the four hybrid orbitals are directed along the four

physical diagonals of the cube and are well adjusted to binding each

atom to its eight neighbours in the cubical volume-centered lattice, the

remaining orbitals being directed towards the edge centers of the

element cell and, possibly, participating in binding the atom to its six

second neighbours /3/p. 99.

 

Let us try to consider relations between exterior electrons of the atom

of a given element and structure of its crystal lattice, accounting for

the necessity of directional bonds (chemistry) and availability of

combined electrons (physics) responsible for galvanic and magnetic

properties.

 

According to /1/p. 20, the number of Z-electrons in the conductivitiy

zone has been obtained by the authors, allegedly, on the basis of

metal's valency towards oxygen, hydrogen and is to be subject to doubt,

as the experimental data of Hall and the uniform compression modulus are

close to the theoretical values only for alkaline metals. The

volume-centered lattice, Z=1 casts no doubt. The coordination number

equals 8.

 

The exterior electrons of the final shell or subcoats in metal atoms

form conductivity zone. The number of electrons in the conductivity

zone effects Hall's constant, uniform compression ratio, etc.

 

Let us construct the model of metal - element so that external electrons

of last layer or sublayers of atomic kernel, left after filling the

conduction band, influenced somehow pattern of crystalline structure

(for example: for the body-centred lattice - 8 ‘valency’ electrons, and

for volume-centered and face-centred lattices - 12 or 9).

-----> Page:

0 [1] [2] [3] [4]

ЗАМОВИТИ ОРИГІНАЛЬНУ РОБОТУ