Rutherford, Ernest appearance

As concerns the spontaneous transmutations undergone by the radioactive elements, the facts appear to indicate (or, at least, can be brought into some sort of order by supposing) the atom to consist of a central nucleus and an outer shell, as suggested by Sir Ernest Rutherford. The nucleus may be compared to the sun of a solar system. It is excessively small, but in it the mass of the atom is almost entirely concentrated. It is positively charged, the charge being neutralised by that of the free electrons which revolve like planets about it, and which by their orbits account for the... 

Scientists initially described radioactivity solely in terms of radiation. The idea of radioactive parf/c/esfirst appeared around the turn of the twentieth century. In 1909, Ernest Rutherford reported confidently that the alpha particle was, in fact, a helium nucleus, jHe, with a 2+ charge. Scientists still had not discovered the proton by this time, so the nature of the helium nucleus (or any other atomic nucleus) was still unknown. In 1919, the existence of the proton was confirmed experimentally by, appropriately enough, Rutherford himself. 

The plum pudding model, a batter of positive charge with minute negative currants embedded in it, appeared to be consistent with experiments which showed that a beam of electrons could pass undeflected through a thin metallic foil. In other words, one might conclude, as Philipp Lenard (1862-1947) did in 1903, that the atom was mostly empty space. These data as well as the larger question about the inner structure of the atom prompted a most provocative line of experimentation by Ernest Rutherford (1871-1937). Manchester University was the site of these historical experiments, which Rutherford initiated soon after he arrived in 1907 to assume his responsibilities as Langworthy Professor of Physics. 

September 12, 1933 1 derive this date from Leo Szilard s statement at Szilard (1972), p. 529, that he read about Ernest Rutherford s speech to the British Association one morning. .. in the newspapers and that day. .. was walking down Southampton Row. The British Association story appeared prominently on p. 7 of The Times on Sept. 12. 

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