large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_68
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
It is still a fact that a quantity of hydrogen combines with eight times its mass of oxygen, so the single oxygen atom must be eight times as massive as the 2 hydrogen atoms taken together. IT IS STILL A FACT THAT A QUANTITY OF HYDROGEN COMBINES WITH EIGHT TIMES ITS MASS OF OXYGEN SO THE SINGLE OXYGEN ATOM MUST BE EIGHT TIMES AS MASSIVE AS TWO HYDROGEN ATOMS TAKEN TOGETHER
cule”.) [Illustration: _John Dalton_] To account for the difference in the masses of the combining gases, Dalton decided that the oxygen atom was eight times as massive as the hydrogen atom. If he set the mass of the hydrogen atom at 1 (just for convenience) then the mass of the oxygen atom ought to be set at 8. These comparative, or relative, numbers were said to be “atomic weights”, so that what Dalton was suggesting was that the atomic weight of hydrogen was 1 and the atomic weight of oxygen was 8. By noting the quantity of other elements that combined with a fixed mass of oxygen or of hydrogen, Dalton could work out the atomic weights of these elements as well. Dalton’s idea was right, but his details were wrong in some cases. For instance, on closer examination it turned out that the water molecule was composed of 1 oxygen atom and 2 hydrogen atoms. For this reason, the water molecule may be written H₂O, where H is the chemical symbol for a hydrogen atom, and O for an oxygen atom. TO COMBINE TO FORM A WATER MOLECULE TO ACCOUNT FOR THE DIFFERENCE IN THE MASSES OF THE COMBINING GASES DALTON DECIDED THAT THE OXYGEN ATOM WAS EIGHT TIMES AS MASSIVE AS THE HYDROGEN ATOM IF HE SET THE MASS OF THE HYDROGEN ATOM AT ONE JUST FOR CONVENIENCE THEN THE MASS OF THE OXYGEN ATOM OUGHT TO BE SET AT EIGHT THESE COMPARATIVE OR RELATIVE NUMBERS WERE SAID TO BE ATOMIC WEIGHTS SO THAT WHAT DALTON WAS SUGGESTING WAS THAT THE ATOMIC WEIGHT OF HYDROGEN WAS ONE AND THE ATOMIC WEIGHT OF OXYGEN WAS EIGHT BY NOTING THE QUANTITY OF OTHER ELEMENTS THAT COMBINED WITH A FIXED MASS OF OXYGEN OR OF HYDROGEN DALTON COULD WORK OUT THE ATOMIC WEIGHTS OF THESE ELEMENTS AS WELL DALTON'S IDEA WAS RIGHT BUT HIS DETAILS WERE WRONG IN SOME CASES FOR INSTANCE ON CLOSER EXAMINATION IT TURNED OUT THAT THE WATER MOLECULE WAS COMPOSED OF ONE OXYGEN ATOM AND TWO HYDROGEN ATOMS FOR THIS REASON THE WATER MOLECULE MAY BE WRITTEN H TO O WHERE THE H IS THE CHEMICAL SYMBOL FOR A HYDROGEN ATOM AND O FOR AN OXYGEN ATOM
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