Book Title: Microcosmology Atom in Jain Philosophy and Modern Science
Author(s): Jethalal S Zaveri, Mahendramuni
Publisher: Jain Vishva Bharati
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Atom in Modern Science
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The first real step forward in an understanding of the structure and the various chemical and physical properties of matter was taken when it was accepted that atoms were not simple indivisible particles of various shapes and sizes, but on the contrary rather complex mechanisms with a number of independent parts in motion.
At the turn of the century, inexplicable phenomena connected with the structure of atom were discovered. Discovery of a new radiation - X-ray-gave the first indication that the atom had some structure. Radio activity gave definite proof of the complex nature of atom, when it was discovered that radioactive substances not only emit radiations but also transform themselves into atoms of new substance.
PLANETARY MODEL
In 1904, famous British physicist J.J.Thomson successfully proved that the atoms of various chemical elements consist of positively and negatively charged components. They are held together by the forces of electric attraction. He called the negatively charged particles electrons, a large number of which were floating in the interior of a mass, with a uniformly distributed positive charge. The atom on the whole is electrically neutral because the total charge of all negative particles equals the total positive charge. The electrons were assumed to be bound comparatively loosely to the body of the atom and one or several of them could be removed by the process of ionisation. Thomson was able to estimate the mass of an electron which turned out to be very small indeed. According to his estimate the mass of a whole hydrogen atom is 1840 times the mass of an electron. This indicated that the main portion of atomic mass is contained in its positively charged components. Thomson was, however, very far from the truth concerning the uniform distribution of the positive charge through the body of the atom.
In 1911, another British scientist Ernest Rutherford, called the father of modern atom, realized that so-called alpha particles emanating from radio-active substances can be used as high speed
