The Last Sorcerers The Path from Alchemy to the Periodic Table (2003) / Chapter Skim
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8. Problems with Atoms
8. Problems with Atoms
Pages 145-156
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From page 145... ...
Warned by the rector of the school at his graduation that his lack of ambition "justified only (1oubtful hopes," Berzelius nevertheless went on to stu(ly medicine at the University of Uppsala, where he became interested in chemistry and got permission to do experiments in the chemistry professor's laboratory. After Berzelius gra(luate(1 in 1802, a wealthy mine owner offere(1 him the use of his home laboratory, where in 1803 he discovered a new element, cerium.
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From page 146... ...
Berzelius's own experiments soon convinced him that Dalton was right to conclude that atoms always combine with one another in small whole-number ratios. Berzelius realized that determining the relative weights of al/l/ of the elements would be of enormous value to chemistry, because it would then be possible to determine the exact composition of any chemical compound.
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From page 147... ...
Because Berzelius's atomic weight determinations did not always agree with Dalton's, they were greeted with some skepticism at first, especially in Englan(l. However, as chemists throughout Europe performed their own atomic-weight experiments, acceptance of his results grew.
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From page 148... ...
In 1808 the French chemist and physicist Joseph Louis Gay-Lussac discovered a simple chemical law and chemists slid not know how to explain it.
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From page 149... ...
When he was 25 Gay-Lussac met the German naturalist Alexander van Humboldt. The two soon found themselves discussing the composition of water and decided to perform some experiments.
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From page 150... ...
The theory couldn't be abandoned; by this time it had become an integral part of chemistry. A SOLUTION FOUND Amedeo Avogadro was born in Italy inl 776 into a line of ecclesiastical lawyers.
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From page 151... ...
Gay-Lussac's results, Avogadro believed, could easily be explained if one assumed that those gasses are made up of molecules containing pairs of atoms. The chemical formula for oxygen gas, for example, is not O but rather O2.
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From page 152... ...
When the rebellion failed, Cannizzaro, who had been an artillery officer and a deputy to the newly formed revolutionary Sicilian parliament, was condemned to death. However, he managed to escape to France, where he found work in the laboratory of the Parisian chemist Michel-Eugene Chevreul.
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From page 153... ...
"Instead of taking for your unit of atomic weight the weight of an entire molecule of hydrogen," Cannizzaro said, "take rather half of this weight." At the time, hydrogen was usually assigned a weight of 1, so when the confusion surrounding the weight of hydrogen was cleared up, numerous other difficulties rapidly disappeared. LOOKING; FOR PATTERNS Chemists still didn't know why there were so many different chemical elements or whether any patterns coul(1 be foun(1 in them.
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From page 154... ...
In 1862 the French geologist and mineralogist Alexandre Chancourtis arranged the elements on a cylinder that he called a "telluric screw." Placing the elements along a descending spiral according to their atomic weights, Chancourtis found that the elements could be placed in vertical groups so that the property of any given element was similar to the ones above and below it. Chancourtis ha(1 (liscovere(1 a pattern.
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From page 155... ...
When Newlands described his scheme at a meeting of the Chemical Society in 1866, the chemist and physicist George Carey Foster sarcastically suggested that Newlands might just as well have arranged the elements alphabetically. Foster's point was that the analogies that Newlands saw could easily be the result of coincidence.
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From page 156... ...
Their methods were too rigid, and they didn't allow for the inclusion of asyet-undiscovered elements. Both men had caught glimpses of a periodicity in the chemical elements, but they weren't able to work out important detailsw or persuade their contemporaries of the significance of what they were trying to do.
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