STRUCTURE OF MATTER

Hokitika Guardian, 18 September 1925, Page 4

STRUCTURE OF MATTER

ATOMS AND ELECTRONS. RUTHEREORD’S EXPERIMENTS. (Mv Autolyuus in " Sydney Herald.") Even the earliest students ol nature recognised the possibility of all matter being composed ol the one ultimate, substance. It was difficult to imagine that the thousands ol materials in the world were all ol various origin, and that, if they were divided to the finest possible particle, they would still be different. But the idea, now accepted as a fact, that all matter lias for its foundation the one primordial substance. seems equally baffling. It is bal'd, front an everyday conception oi things, to imagine that yvator, to take an instance purely at random, is made up of the same substance as iron ; that the basis of treacle is similar, when carried to its utmost divisibility to that of Hour, and so oil. )el practically every physical science has to recognise this lad. and chemists, electricians. yy ire less technicians, meteorologists, ast ronoiners, doctors, and all students of the lev-paths of these sciences, accept it without question. If this theory, then, is taken for granted—and quite a lot ol physics lias to he so taken, in spite of the extent of practical research—another theory, running parallel to it. must also ice recognised. This is the idea that all matter, if fundamentally the same, must he divisaldc into particles, infinitely small, but to modern science, actually measurcablo and ponderable nevertheless. There were many early

physicists who held that all matter continued on indefinitely, and was never ultimately divisible into finite particles. Goethe was amongst those who believed this, but the idea also 1n,,1 support trom the more practical scientists of the time. But in the light of more recent research the theory has Intel to be absolutely abandoned, and in its place has been advanced, and universally accented, the atomic and electronic theory ol the structure id mat ter. Rcynnd a definite point the human imagination refuses to function. \\ c can gain some idea ot what a thousand years mean, ten- instance; but to most minds ten thousand years are simply a number yvith no meaning behind itSimilarly, we can picture something ol a certain minuteness, but there is a point at yvhich the imagination halts. In spite of this, scientists have measured. weighed and counted particles of matter of which the most tar-flung comparison give's no conception. Even tile ti Ist division into which any material can he segregated the molecul —i- beyond this point. \ct the molecule is huge compared with the ultimate particle. Next on the scale is the atom, and alter that the eh" troll, which represents, as lar as practical research has penetrated, the keystone of all matter. The molecule, is in a sense, a mixture of atoms; and an atom rep resents the unit of the 92 elements which are known to exist. Alter lie atom comes the electron the smalle-t milt o! matter known. What, lhen. constitutes the dilfereiie.' lie tween all of the P2 elements and their atone—between hydrogen, the lightest gas a,ml uranium. the heaviest metal—between lead and aluminium, and so on. A PLANETARY SYSTEM. The slow of tlte structure of the atom may be summari-td in likening it to a planetary -y-tcin. Hut before' entering on the mechanical aspect of the atom the cha rae tel i-t ies el Ihe 1 suh-a I mil ie particle, the electron, must Ice examined. .Many scientist;, leave regarded the electron a- being artual--1 }y electricity, which brings u.s to the , amazing conclusion that all matter is ! .'imply —-elect rieity. Hut whether or not the electron I-, in itself, vice I ric- , it,\. scarcely alleil- the object oi this article; this angle is 100 nhtu-e to be ‘ regarded more than cursorily. it lias to' I", realised, however, that every electron carries an electric- charge or , pciteiilial. either positive or negative ; ' and the entire stability of the universe i is dependent upon the balancing of : these varieties of electricity. If there . are more negative electrons at one end ol a coiidtii tor than at the other, there I will lie a flow of electricity to restore the habitue such is any electric current. " Nature unha lanced" is inconceivable; there must be an equal nitm- : her of negative and positive electrons in tbc universe. Hut the positive j electron, to isc all Irishism, is not an j electron at all ; it i- a " proton."

Due of tin' leading physicist., the j world lias known. Professor d. d. | T iiomsnn, pictured the atom as eon- - .sisting ot one or more protons, or , (simply a mass of positive electricity, with a .suitable number of electrons to , balance this positive mas-. Tim the positive and negative charges '■■ ie neutralised. For even- different element in the table of P'2, running front hydrogen to uranium, another electron 1 was added, with, of course, a suitable • unit ol positive clini'”/ 1 Lo balance it. Rut this com option et I lie atom was , lacking in certain characteristics, though correct in many ways which other imp irLnnl aspects dviivmdod, and. when, in IPII. Fir Ernest Rulhcrlord gave to the world his picture of the atom. d. d. Thomson’s idea had to be extensively modified. HUTTIKRFORD'S ATOM. I lie study ol tic- structure of matter lias drawn within its ambit some of tile most hi'illiani minds given the world. Aie.ioig-i them can lie mentioned John Dalton. A vogadr". Prom, Pro-fe--or J .1. Ti-mi.-oii. Dr Neils Bohr, and Sir (liner lodge. But, perhaps, the niosi bi-iron- of living scientists is Sir Ernest Rutherford, whom Sydney is soon to have the opportunity ~| i bearing. An outstanding Figure in physical research, be is noted for his ability as a sneaker and For the spectacular nature ol bis addresses. The atom which Rutherford lias postulated and demonstrated almost conclusively by practical experiment to lie .true in its essential-, consists ~f a nucleus made of both electrons and proton positive and negative charges-. For every different element the makeup of the atom’s nucleus varies in a complicated manner. The nuclei differ in weight, sjyo, and in the proportion of electrons and protons they contain. Rut one important fact emerge- from the intricacies of these nuclei, and that i- the resultant positive charge, or protons too many, a- it were, which oath carric-. The nucleus of the hydrogen atom, for example (the lightest and simplest of all atoms) merely consists of one proton, one unit of positive electricity. To go to the other extreme, uranium lias the most complicated nucleus of all atoms, but. Iwitig last on the list of elements, and the heaviest, it carries a positive charge of P'2 units—the nucleus is itnbalanced by this number of atoms. It has been said that all atoms arc electrically stable, and this necessitates some means of neutralising the nuclei. This cancelling of the positive charge is done bv further electrons additional to those in the nucleus--which revolve around the nucleus at a sjH'eil too great tor our sou-o to gra-p. But that it i- an actual, physical movement there is no doubt

whatever. It lias been seen, in effect, and recently the movements of electrons have been heard. Stranger still, both the nucleus and the electrons revolving around it are only an infinitesimal part of the actual size ol the atom: in other words, the size of the atom is measured by the orbit of its outside electrons. The relation of the size of an electron to the size of the atom of which it is so small a. part has been summed up by Sir Oliver Lodge in his well-known simile, in which lie likens the electron in an atom to " a bee in a cathedral.’’ To instance once more the simple hydrogen atom, the one electron it contains is rather less than 2000 times smaller than the total size ol the atom. Now the heavier the element, broadly speaking, the greater the number of electrons it has revolving, planet-fash-ion, around its nucleus, and t'hen the number approaches the end ol the table their orbits necessarily become highly complicated, and some, it has been found, arc more mechanically unstable than others. When the extremely heavy elements are readied, such as radium. actinium, and uranium, the structure becomes next to impossible mechanically, and disintegration begins. Klcctrons furthest from the nuclei. which are unable to hold them, fly dll' ironi the atoms, to remain stray units of negative electricity until atom-, known a- ions, which have for some reason lost an electron or. and more, pick them up to the benefit of both electron and atom. One ”! tor Kniesl Rutherford's lectures will cov- ;.]• •■The Disintegration of Atoms. 1.0 which added interest may he given hv this brief survey.

Very aptly has this coneoptiou of the atom been attributed to Rutherford. It is true that the essentials ol it were proposed by a scientist named Naguoka in It-11, but it was left to Rutherford to expand the theory and demonstrate its feasibility by practical experiment. More recently Rutherford's researches have dealt with the artun! structure of the nuclei of dm atoms of different elements by bombarding them with particles thrown off hv other atoms. Hut this phase is too intricate t" mention here. In radioaet'ivitv. too. Sir l'irnost Rutherford’s name lim'd always he eottpled, and for „>j,ny years the study of radio-active substances—radium, actinium, uranium. and those elements whose mechanical structure renders them unstable and are lonstamly losing electrons—lias received his particular attention. Of such stuff, then, is the world imilt on. It can lie called "inorganic chemist! v ” or merely "physics”; but surrounding the subject is some of the imnalire of exploration into hitherto unknown regions, and so mg ot th" glamour of the bizarre and wonderlul. The visit. and the views, of one of the foremost exponents ol the sciene.'* should more* than rouse the interest, o, mailv besides those to whom the subject is already familiar.