HOW AN ATOM EXPLODES

Hokitika Guardian, 2 December 1929, Page 8

HOW AN ATOM EXPLODES

PARTICLES MOVING AT 100,000 MILES A SECOND. (By Dr. W. A. Wooser in “Daily Mail.” An atom is like a school. In the centre is the nucleus a heavy, charged body, the masters of the school, controlling all the rest. Within the nucleus is a very concentrated store of force called the subnucleus, and rotating round it are much smaller and less charged bodies held in place by their mutual repulsions. These are the headmaster and his assistants. Then at different distances from the nucleus are the elections, which are very much smaller and oppositely charged,.and well represented by the classes of pupils at the scnool. An atom can explode in three ways, disturbance arises in the nucleus and one of its smaller and less charged parts is shot out with great speed as an alphapartiele. This speed may be as high as 10,000 miles a second, which is far greater than any we can produce by explosives, for the initial velocity of a shell, capable of travelling 60 miles, is only 2 miles per second. Alter this eruption the assistant masters shuffle. places and the atom goes on merrily until another explosion occurs. The time between successive disturbances is governed by the same law as that which decides whether Oxford or Cambridge shall win the toss in the Boat Race, i.e. it is a matter of chance. Sometimes an atom lives a .million years, sometimes only a day.

RAYS CAUSE EXPLOSIONS. These swift particles aj’e very dangerous when they come near other atoms, for they are. more potent than any projectile that we can make. They penetrate into the very heart of any atoms'winch get in their way and occasionally knock parts out of them. This piocess has been studied especially by oir Ernest Rutherford, who has shown how atoms which would otherwise be quite peaceful, and not liable to explode, can be made to ao so under the action of these swift rays. The second form, of disintegration which an atom shows is paraded by the expulsion of a small boy from the school—in other words, an electron is shot out from the atom when it is called a beta-ray. These expulsions are of two kinds; in one the electrons come out with deiinite speeds and in the other, they travel with velocities varying continuously over a wide range. The electrons emerging with definite speeds give us a very good clue to the character of the atom. They show that the atom is divided in its outer parts into strictly separated regions in,,each ,of which the electrons have deiinite energies.

The other electrons of nondescript energies were for a long time a thorny problem, because it was hard t-o understand how an atom which appeared to be from,all other experiments a beautifully ordered structure could have one part of it quite haphazard. It was as though, in our school of analogy, ui re class had run wild? and was continually going in and out of the class-rooms oi the orderly pupils.

MYSTERIOUS RADIATION. By a very delicate experiment which involved the measurement of an amount of heat causing a rise in.temperature of only l/10,(K)0deg. C. Dr Ellis and I were able to show that these vagrant electrons really came from the nucleus and not from the outer parts of the atom. Thus the disorder exists in the masters’ common-room not in the classes !

The third way an atom breaks up is much more mysterious, it gives out an invisible radiation called gammarays. This is so powerful that it can burn away half an inch of body tissue and is much used because of this in cancer research. The nucleus is certainly responsible for this influence. It is not yet discovered by what mechanism the disturbances in the nucleus give rise ,to the penetrating radiation, though there is a very close connection between the expulsion of an electron and gammaray. Though our knowledgeyabout the insides of atoms is rapidly improving we are a long way off complete understanding, and until then we cannot hope to make use of the energy in atoms for our material needs.