STRUCTURE OF ATOMS.

Hokitika Guardian, 5 July 1924, Page 4

STRUCTURE OF ATOMS.

SOLAR SYSTEMS,

IBY SCIENCE SERVICE.)

Although an atom has been likened to a solar system, thero is the difference that if some great star came shooting into the solar system it would never be the same again, while an atom can he bombarded with electrons and shortly recover its previous state. Sir Ernest Rutherford, president of the British Association for the Advancement of Science, declares in a stateEoundatiou of New York. Explaining the electrical structure of matter. Professor Rutherford says: —"All men deal with matter in the gross, and our bodies are of it constructed. .Mysteries of matter therefore. have fascination for thoughtful laymen, as well as scientists and technologists. The atom has long been familiar as the ultimate unit of mutter.

“While the vaguest ideas wore held as to the possible structufc of atoms there was a general belief among tho more philosophically minded that the atom could not he regarded as simple unconnected units. For the clarilying of these some what vague ideas the proof in 1897 of the independent existence of the electron as a mobile electrified unit, of mass minute compared with that of iTie lightest atom, was of extraordinary importance.

"Our whole conception of the atom was revolutionised by the study of rad-io-activity. The discovery of radium provided the experimenter with powerful sources of raditiou, specially suitable for examining the nature of the characteristic raditions emitted by the radio-active bodies in general. 'I he wonderful succession of changes that occur in uranium, more than thirty in number was soon disclosed. "It was early surmised that elertricitv was atomic in nature. Ibis

view was confirmed and extended by a study of tlie changes of electricity carried by electrons. Skilful experiments by physicians atlded to the knowledge of the subject. One of the main difficulties has been the uncertainty as lo the relative part played by positive anti negative electricity in the struct tire of the atom. The electron has a negative charge of one fundamental unit, while the charged hydrogen atom has a charge of one positive unit. 'I here is the strongest evidence that the atoms of matter are built up ol these two electrical units.

"It. may he of interest to try to visualise the conception of the atom we Im ve so far reached by taking for illustration the heaviest atom, uranium. At the centre of the atom is a minute nucleus surrounded by a swill-

ing group of 9” elect t ons, all m motion in definite orbits, and occupying, but by iio means lining, a volume very large compared with that ol the nucleus. .Some of the electrons desert he nearly circular orbits round the nucleus; others, orbits of a more elliptical shape, whose axe- rotate rapidly round the nucleus. The motion of the electrons in the dilferent groups i- not necessarily confined to a definite region of the atom, lint the electrons of one group may penetrate deeply into the region mainly occupied by another

group, thus giving a type of inter-con-nection or coupling between the various groups. Tile maximum speed ot any electron ocpends oil the closeness of the approach to the nucleus, but the outermost electron will have a minimum speed of more than (lt)0 miles per second, while the innermost electrons have an average speed of more than ‘.1(1,000 miles per second, or half the i need of light. "The nucleus atom has often been likened to a solar system, where the silo corresponds to tile nucleus and the planets to the electrons. The analogy, liouever, must not he pressed too Jar. Suppose, for example, we imagined that some large and swift, celcs-

li.il ii-itoi traverses and escapes from

our solar system without any catastrophe to itsell or the planets. There Will inVvitahly result permanent changes in the lengiTis ol the month anti year, and our system will never return to it- original state. Contrast those with the effect of shooung an electron through the electronic structure of the atom. The motion of many of the electrons will he disturbed by

its passage, and in special cases an elect roll tuny he removed from its orbit and hurled out ol its atomic system.

In a short time smother electron will fill into the vacant place from one of the outer groups, and this vacant place in turn will lie filled up, and so on until tin* atom is again reorganised, f>• all eases the filial state of the electronic system is the same as in the boginning.”