large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_136
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
When the uranium atom gives off an alpha particle, it forms an atom originally called "uranium X₁". On close investigation, it turned out that this uranium X₁ had the chemical properties of thorium. WHEN THE URANIUM ATOM GIVES OFF AN ALPHA PARTICLE IT FORMS AN ATOM ORIGINALLY CALLED URANIUM X ONE ON CLOSE EXAMINATION IT TURNED OUT THAT THIS URANIUM X ONE HAD THE CHEMICAL PROPERTIES OF THORIUM
alpha particles, a new kind of atom was formed that was not uranium at all. It was this new atom that was eventually found to give off a beta particle, and then another atom of still another element was formed. This work of Rutherford and Soddy began a line of investigation that by 1907 had shown that there was a whole radioactive chain of elements, each one breaking down to the next in line by giving off either an alpha particle or a beta particle, until finally a lead atom was formed that was not radioactive. [Illustration: _Frederick Soddy_] There was, in short, a “radioactive series” beginning with uranium (atomic number 92) and ending with lead (atomic number 82). The same was true of thorium (atomic number 90), which began a series that also ended with lead. Still a third element, actinium (atomic number 89) was, at that time, the first known member of a series that also ended in lead. The various atoms formed in these three radioactive series were not all different in every way. NIUM ADAMS GAVE OFF ALPHA PARTICLES A NEW KIND OF ATOM WAS FORMED THAT WAS NOT URANIUM AT ALL IT WAS THIS NEW ATOM THAT WAS EVENTUALLY FOUND TO GIVE OFF A BATTER PARTICLE AND THEN ANOTHER ATOM OF STILL ANOTHER ELEMENT WAS FORMED THIS WORK OF RUTHORD AND SODDY BEGAN A LINE OF INVESTIGATION THAT BY NINETEEN O SEVEN HAD SHOWN THAT THERE WAS A WHOLE RADIOACTIVE CHAIN OF ELEMENTS EACH ONE BREAKING DOWN TO THE NEXT IN LINE BY GIVING OFF EITHER AN ALPHI PARTICLE OR A BEETA PARTICLE UNTIL FINALLY A LEAD ATOM WAS FORMED THAT WAS NOT RADIOACTIVE THERE WAS IN SHORT A RADIOACTIVE SERIES BEGINNING WITH URANIUM ATOMIC NUMBER NINETY TWO AND ENDING WITH LEAD ATOMIC NUMBER EIGHTY TWO THE SAME WAS TRUE OF THORIUM ATOMIC NUMBER NINETY WHICH BEGAN A SERIES THAT ALSO ENDED WITH LEAD STILL A THIRD ELEMENT ACTINIUM ATOMIC NUMBER EIGHTY NINE WAS AT THAT TIME THE FIRST KNOWN MEMBER OF A SERIES THAT ALSO ENDED IN LEAD THE VARIOUS ATOMS FORMED IN THESE THREE RADIOACTIVE SERIES WERE NOT ALL DIFFERENT IN EVERY WAY
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