large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb_236
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_01_asimov_64kb
English
12904
The atomic weight of chlorine was close to 35. THE ATOMIC WEIGHT OF CHLORINE WAS CLOSE TO TH
ed in 1828. At first he called the atomic weight of oxygen 100. Then he decided to make the atomic weights as small as possible, without allowing any atomic weight to be less than 1. For that reason, he set the atomic weight of oxygen at exactly 16 and in that case, the atomic weight of hydrogen had to be placed just a trifle higher than 1. The atomic weight of hydrogen became 1.008. This system was retained for nearly a century and a half. Throughout the 19th century, chemists kept on working out atomic weights more and more carefully. By the start of the 20th century, most elements had their atomic weights worked out to two decimal places, sometimes three. A number of elements had atomic weights that were nearly whole numbers on the “oxygen = 16” standard. The atomic weight of aluminum was just about 27, that of calcium almost 40, that of carbon almost 12, that of gold almost 197, and so on. On the other hand, some elements had atomic weights that were far removed from whole numbers. E DECIDED TO MAKE THE ATOMIC WEIGHTS AS SMALL AS POSSIBLE WITHOUT ALLOWING ANY ATOMIC WEIGHT TO BE LESS THAN ONE FOR THAT REASON HE SET THE ATOMIC WEIGHT OF OXYGEN AT EXACTLY SIXTEEN AND IN THAT CASE THE ATOMIC WEIGHT OF HYDROGEN HAD TO BE PLACED JUST A TRIFLE HIGHER THAN ONE THE ATOMIC WEIGHT OF HYDROGEN BECAME ONE POINT ZEROZERO EIGHT THIS SYSTEM WAS RETAINED FOR NEARLY A CENTURY AND A HALF THROUGHOUT THE NINETEENTH CENTURY CHEMISTS KEPT ON WORKING OUT ATOMIC WEIGHTS MORE AND MORE CAREFULLY BY THE START OF THE TWENTIETH CENTURY MOST ELEMENTS HAD THEIR ATOMIC WEIGHTS WORKED OUT TO TWO DECIMAL PLACES SOMETIMES THREE A NUMBER OF ELEMENTS HAD ATOMIC WEIGHTS THAT WERE NEARLY WHOLE NUMBERS ON THE OXYGEN EQUALS SIXTEEN STANDARD THE ATOMIC WEIGHT OF ALUMINIUM WAS JUST ABOUT TWENTY SEVEN THAT OF CALCIUM WAS ALMOST FORTY THAT OF CARBON ALMOST TWELVE THAT OF GOLD ALMOST ONE HUNDRED NINETY SEVEN AND SO ON ON THE OTHER HAND SOME ELEMENTS HAD ATOMIC WEIGHTS THAT WERE FAR REMOVED FROM WHOLE NUMBERS
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