large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_155
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
The uranium series ought to end with lead atoms that had an atomic weight of 206. THE URANIUM SERIES OUGHT TO END WITH LEAD ATOMS THAT HAD AN ATOMIC WEIGHT OF TWO
ium B one of 11 hours, and actinium B one of 36 minutes. In 1913 Soddy called atoms that were in the same place in the list of elements, but which had different radioactive properties, “isotopes”, from Greek words meaning “same place”. At first, it seemed that the only difference between isotopes might be in their radioactive properties and that only radioactive atoms were involved. Quickly that proved not to be so. It proved that it was possible to have several forms of the same element that were all different even though none of them were radioactive. The uranium series, the thorium series, and the actinium series all ended in lead. In each case the lead formed was stable (not radioactive). Were the lead atoms identical in every case? Soddy had worked out the way in which atomic weights altered every time an alpha particle or a beta particle was given off by an atom. Working through the three radioactive series he decided that the lead atoms had different atomic weights in each case. M B ONE OF ELEVEN HOURS AND ACTINIUM B ONE OF THIRTY SIX MINUTES IN NINETEEN THIRTEEN SODDY CALLED ATOMS THAT WERE IN THE SAME PLACE IN THE LIST OF ELEMENTS BUT WHICH HAD DIFFERENT RADIOACTIVE PROPERTIES ISOTOPES FROM GREEK WORDS MEANING SAME PLACE AT FIRST IT SEEMED THAT THE ONLY DIFFERENCE BETWEEN ISOTOPES MIGHT BE IN THEIR RADIOACTIVE PROPERTIES AND THAT ONLY RADIOACTIVE ATOMS WERE INVOLVED QUICKLY THAT PROVED NOT TO BE SO IT PROVED THAT IT WAS POSSIBLE TO HAVE SEVERAL FORMS OF THE SAME ELEMENT THAT WERE ALL DIFFERENT EVEN THOUGH NONE OF THEM WERE RADIOACTIVE THE URANIUM SERIES THE THORIUM SERIES AND THE ACTINIUM SERIES ALL ENDED IN LEAD IN EACH CASE THE LEAD FORMED WAS STABLE NOT RADIOACTIVE WERE THE LEAD ATOMS IDENTICAL IN EVERY CASE SODDI HAD WORKED OUT THE WAY IN WHICH ATOMIC WEIGHTS ALTERED EVERY TIME AN ALPHA PARTICLE OR A BATA PARTICLE WAS GIVEN OFF BY AN ATOM WORKING THROUGH THE THREE RADIOACTIVE SERIES HE DECIDED THAT THE LEAD ATOMS HAD DIFFERENT ATOMIC WEIGHTS IN EACH CASE
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