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22 TIE JAINA PHILOSOPHY our attention to the nature of forces which bind together the atoms of different clcnicnis into complex molcculcs of innumerablc chemical compounds The chemical bond between the neighbouring atoms in a molecule is due to the interaction of the elcctronic shells and the forces involved arc comparatively small The distinction between the atomic nuclei and the electronic shells of different clements at once gives a proper explanation of the various pliysical and chemical properties of the clcments and also or the fact that they are the last units of matter The chemical properties of atoni are however, controlled by the nucleus If one wants to change the chemical properties of an atom, one has to change the nucleus and this requires energies about a million times greater
ELEMENTARY PARTICLES
Atoms of all material elements are complicated mechanical systems with a number of clectrons rotating round the central nucleus Are these atoms the ultimate units of matter? Can we sub-divide them still further into smaller and simple particles? Would it be possible to reduce all different atoms to perhaps a few really simple particles?
In the middle of the last century, William Prout, an English chemist put forth a hypothesis that the atoms of all elements are made up of various numbers of hydrogen atoms This hypothesis was based on the fact that the atomic weights of various elements were in most cases very nearly exact multiples of that of hydrogen. Thus atoms of oxygen which are sixteen times heavier than those of hydrogen, must be composed of 16 hydrogen atoms somehow stuck together But the facts as found at that time were
