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27. Natural Reality / B. Chemistry / 3. Periodic Table

[arrangement of modern elements in a pattern]

17 ideas
Mendeleev had a view of elements which allowed him to overlook some conflicting observations [Mendeleev]
Mendeleev focused on abstract elements, not simple substances, so he got to their essence [Scerri on Mendeleev]
The periodic table not only defines the elements, but also excludes other possible elements [Azzouni]
Generally it is nuclear charge (not nuclear mass) which determines behaviour [Hendry]
Elements were ordered by equivalent weight; later by atomic weight; finally by atomic number [Scerri]
Moseley showed the elements progress in units, and thereby clearly identified the gaps [Scerri]
Moseley, using X-rays, showed that atomic number ordered better than atomic weight [Scerri]
Some suggested basing the new periodic table on isotopes, not elements [Scerri]
Elements are placed in the table by the number of positive charges - the atomic number [Scerri]
Pauli explained the electron shells, but not the lengths of the periods in the table [Scerri]
Elements in the table are grouped by having the same number of outer-shell electrons [Scerri]
Orthodoxy says the periodic table is explained by quantum mechanics [Scerri]
To explain the table, quantum mechanics still needs to explain order of shell filling [Scerri]
Since 99.96% of the universe is hydrogen and helium, the periodic table hardly matters [Scerri]
The best classification needs the deepest and most general principles of the atoms [Scerri]
Mendeleev systematised the elements, and also gave an account of their nature [Weisberg/Needham/Hendry]
Chemistry just needs the periodic table, and protons, electrons and neutrinos [New Sci.]