Electron theory

“ The atomic hypothesis is thus raised to the position of a scientifically well-founded theory.
II. GROWTH OF ELECTRICAL THEORIES
The granular theory of electricity, while unlike the atomic and kinetic theories of matter in that it can boast no great antiquity in any [Pg 11] form, is like them in that the first man who speculated upon the nature of electricity at all conceived of it as having an atomic structure. Yet it is only within very recent years—thirty at the most—that the modern electron theory has been developed. ”

“ Jimmy looked relieved.
“Now,” continued the doctor, “the theory is that all matter is composed of an infinite number of electrons. An electron is the smallest thing that can be conceived, smaller even than the atom which used to be thought of as the unit. There may be millions, billions, quadrillions of them in a thing as big as a hickory nut. And when these electrons get busy you can look out for things to happen.
“Every hot object sends out electrons. That’s the reason that the filament in the electric light tube sends them out.” ”

“ One of the most vital assertions made in Einstein’s theory is that the kinetic energy with which monochromatic light ejects electrons from any metal is proportional to the frequency of the light, i.e., if violet light is of half the wave-length of red light, then the violet light should throw out the electron with twice the energy imparted to it by the red light. ”

“ When the electron has come in so close to the nucleus that the distances in the inner system cannot be assumed to be small in comparison to the distance of the outer electron from the nucleus, the situation is changed. The force with which the nucleus and the inner electrons together will work upon the outer electron will be appreciably different from the inverse square law of attraction of a point charge. ”

“ This electronic hypothesis, therefore, affords a basis on which we can build up a theory affording an explanation of the nature of the intimate connection known to exist between ether, matter and electricity. The electron is the connecting link between them all, for it is in itself a center of convergent ether strain; isolated, it presents itself as electricity of the negative or resinous kind ”

“ Here is the electron, the atom of electricity demanded by the theory of Lorentz.
But what of the positive electron? Search for this has often been made, but the mass of the positively charged particles has always proved to be comparable with that of an atom. There are some indications that positive electrons may be identical with positively charged atoms of hydrogen or of the gas helium whose atomic mass is four times that of hydrogen; but for the present we can say only that positive electricity is never found dissociated from matter of atomic dimensions. ”

“ Furthermore in the calculation of the work corresponding to the energy levels we must take account not only of the interaction between, the electrons in the normal state of the atom, but also of the changes in the configuration and interaction of the remaining electrons, which establish themselves automatically without emission of radiation during the removal of the electron. ”

“ The electron and the positive charge produce an electric field all round them, and an electric field is probably a very complicated piece of mechanism. We may picture it in this case as consisting of a large number of lines of force, with one end on the electron and the other on the positive charge, spreading out into the space round the atom, and we may also suppose that these lines of force may move about even though their ends are at rest, and thus vibrate independently of the electrons. ”

“ The energy of the escaping electron must come, then, in some way or other, from the incident light, or from other light of its frequency, since it is characteristic of that frequency alone.
When, however, we attempt to compute on the basis of a spreading-wave theory how much energy an electron can receive from a given source of light, we find it difficult to find anything more than a very minute fraction of the amount which it actually acquires. ”

“ According to this still very new theory, which is supported by very convincing facts, the electrons are to be imagined as arranged in concentric shells (like the layers of an onion) , among which the innermost shell plays a distinctive part inasmuch as the number of the electrons arranged in it decides the chemical character of the atom in question. It sometimes occurs that electrons spring, under external influence, from one orbit to another; when the electron jumps back to the original orbit, light is emitted. ”

“ By observing the behaviour of the electron under electric and magnetic forces, the values of its mass and electric charge—the quantities which determine its behaviour under specified conditions—have been measured; indeed, though the electron has only lately come under our notice, we know a good deal more about it than we do of many things which have been discovered centuries ago. ”

“ For one thing, the free-moving electrons, with which we are concerned in cathode rays and in some types of Becquerel rays, give rise to many interesting problems. I will single out only the important question of the so-called apparent mass of these particles. A definite magnetic field in the surrounding ether - and hence also a certain amount of energy in this medium - are inextricably connected with every movement of an electron; we can therefore never set an electron in motion without simultaneously imparting energy to the ether. ”

“ An atom with several electrons can, however, be much more violently [Pg 161] excited from its quiescent state when an electron in the inner region of the atom is ejected by a swiftly moving electron (a cathode ray particle or a β-particle from radium) which travels through the atom. Such an invasion produces a serious disturbance in the stability of the electron system; a reconstruction follows, in which one of the outer, more loosely bound electrons takes the vacant position. In the transitions, in which these outer electrons come in, rather large energy quanta are emitted. ”

“ So far as the negative ion is concerned, the situation at the moment seems to be in favor of the atom-ion theory. There has recently developed strong evidence [19] that although in some very pure gases, such as helium, argon, and even nitrogen, the negative electron cannot find attachment at all, when it does attach so as to form ions of the mobility mentioned above, it carries with it thereafter but a single molecule. ”

“ Of the two kinds of electricity we find but one—the negative—that can be detached from atoms. We find the negative electron too as a constituent of the atom. The electron, whatever its source, is always the same, while the positive charge partakes of the varying nature of the matter with which it is associated. Emphasis is thus laid upon the electrons as forming the true electrical fluid, the positive electricity playing a subordinate part. According to this theory a neutral atom, which we know contains some electrons, contains also enough positive charge to exactly neutralize them. ”

“ We have restricted ourselves to the case where only one electron is removed from the normal state of the neutral atom. It may, however, happen that two electrons are ejected from the atom so that it becomes a positive ion with two charges. When an electron from the outside is approaching this doubly charged ion it will, at a distance, be acted upon as if the ion were a helium nucleus with two positive charges. ”

“ As long as we have to deal only with resolution into three components, it is sufficient explanation to assume that each incandescent atom contains a single electron which can vibrate round its equilibrium position in all directions in the same way. This simple theory however leaves us high and dry as soon as the spectral lines split into more than three components in the magnetic field. ”

“ The insight, that one can conclude the existence of a center and of the charge distribution in concentric layers from the behavior of electrons at quasi-stationary translation, is an additional contribution to fortify the atomistic view of electricity. ”

“ Sub-electron, 161 f., 166, 175, 181 Thomson-Einstein hypothesis, 253 Valency in gaseous ionization, 127 f. Velocity of agitation of molecules, 8; of emission of electrons under monochromatic light, 245 Velocity of drop, 86, 101 Vienna Academy, 153, 175 Viscosity of air, 93 Wave theory, 233, 234 Wien constant , 117, 261 X-rays, 23, 33, 39, 40, 46, 50, 57, 192, 204, 235, absorption of, 199; Duane’s method, 214; frequencies, 202, 246; ionizing agent, 79, 126, 134; and series, 204; and light, 248; mechanism of ionization by, 125; monochromatic 246; photographs of spectra, Fig. 21 ”

“ The light-quanta, by colliding with the free electron necessarily transfers some of its energy to it, and therefore, if it arrives with the energy , it must recoil from the impact at some angle with a smaller energy , and therefore a lower frequency , than that with which it impinged. ”

“ The terms “electron” and “positive electron” would then be used altogether conveniently precisely as are the terms “man” and “woman.” Indeed, the most authoritative writers—Thomson, Rutherford, Campbell, Richardson, etc.—have in fact retained the original significance of the word “electron” instead of using it to denote solely the free negative electron, the mass of which is of that of the hydrogen atom. ”

“ The continued study of the properties of the minute particles of radio-active substances—a new name is needed for those most mutable of material grains—must lead to discoveries of great moment for chemistry and physics. That study has already thrown much light on the phenomena of electric conductivity; it has given us the electron, a particle at least a thousand times lighter than an atom of hydrogen; it has shown us that identical electrons are given off by, or are separated from, different kinds of elementary atoms, under definable conditions ”

“ In other words, if Compton’s assumptions are correct, the photo-electric effect, in which there certainly is such a complete transfer, cannot possibly represent the interaction between a light-wave and a free electron. When the electron is bound in the atom there is no difficulty of this sort, for the huge mass of the atom then permits the momentum equation to be satisfied without forbidding the practically complete transfer of the energy to one of its electrons. ”

“ Electricity is not like red paint, a substance which can be put on to the electron and taken off again; it is merely a convenient name for certain physical laws.
All electrons, whatever kind of atom they may belong to, and also if they are not attached to any atom, are exactly alike—so far, at least, as the most delicate tests can discover. Any two electrons [Pg 26] have exactly the same amount of negative electricity, the smallest amount that can exist. They all have the same mass. ”

“ Although the electrons and the nucleus are charged particles, the atom as a whole is electrically neutral; this means that the positive charge of the nucleus must be equal in magnitude to the total charge of all the negative electrons. All electrons have precisely the same charge, which is the smallest charge that has ever been observed. What is particularly strange and not yet explained is the fact that all other charges are as big as the electron charge, or twice as big, or three times as big, or a million times as big. ”

“ Each of these electrons is in incessant and terrific motion, moving at the rate of something like 180,000 miles a second, so placing it in position would be a difficult matter. Besides which, each electron is not a tiny bit of matter as we ordinarily conceive matter—something which we can touch and handle. It is a mere centre or nucleus of energy. Any placing of it in position by a super-gardener is therefore out of the question. ”

“ Thus the electric atom of the two has the greater claim to simplicity. When we speak of an electric atom disregarding for the time the matter associated with it, we call it, not an ion, but an electron. Evidence will later be given suggesting ways by which we may wrench a negative electron wholly free from matter, and experiment with it in its detached and pure state. ”

“ At the high temperature inside a star the battering of the particles by one another, and more especially the collision of the ether waves (X-rays) with atoms, cause electrons to be broken off and set free. These free electrons form the third population to which I have referred. For each individual the freedom is only temporary, because it will presently be captured by some other mutilated atom; but meanwhile another electron will have been broken off somewhere else to take its place in the free population. ”

“ With 29 electrons it’s no wonder if sometimes one goes wandering off and finally gets into the game about some other nucleus. Of course, an electron from some other atom may come wandering along and take the place just left vacant, so that nucleus is satisfied.
We don’t know all we might about how the electrons wander around from atom to atom inside a copper wire but we do know that there are always a lot of them moving about in the spaces between 15the atoms. Some of them are going one way and some another. ”