ELECTRONS
The inner rings of electrons give rise to X-rays when they are disturbed, and it is chiefly by means of X-rays that their constitution is studied. The nucleus itself is the source of radio-activity.... The most complex atom known is that of uranium, which has, in its normal state, 92 electrons revolving round the nucleus, while the nucleus itself probably consists of 238 hydrogen nuclei and 146 electrons....
Under normal conditions, when the hydrogen atom is unelectrified, the electron simply continues to go round and round the nucleus, just as the earth continues to go round and round the sun. The electron may move in any one of a certain set of orbits, some larger, some smaller, some circular, some elliptical. But when the atom is undisturbed, it has a preference for the smallest of the circular orbits, in which the distance between the nucleus and the electron is about half a hundred-millionth of a centimetre. It goes round in this tiny orbit with very great rapidity; in fact its velocity is about a hundred-and-thirty-fourth of the velocity of light, which is 186,000 miles a second. Thus the electron manages to cover about 1,400 miles in every second. To do this, it has to go round its tiny orbit about seven thousand milliontimes in a millionth of a second; that is to say, in a millionth of a second it has to live through about seven thousand million of its “years”!
Such figures, such facts, stagger the imagination. The mind of man cannot really conceive them. And yet we know that they are not fanciful; calculations and indirect measurements have been made with the utmost exactitude. And, after all, the infinitely little is no more staggering than the infinitely great. For in astronomy we know that stars billions of miles distant from us in space have been seen, measured, photographed and analyzed. Tens of thousands of “light-years” separate us from them (i. e., space which would be travelled by light, speeding at 186,000 miles a second). And yet the structure of the atom closely resembles the planetary system! Is the whole Universe, great and small, built according to the same plan, according to the same model? It would appear so!
It will be seen from the above that the modern science of chemistry overlaps other sciences in many directions—physics, biology, astronomy, etc. These sciences are to a certain extent now inter-woven and inter-blended. Where the one ends and the other begins it is hard to say. Again we see the importance of co-operation in these various fields of inquiry!