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| What is the Periodic Table Showing? | Periodicity |
The INTERNET Database of Periodic Tables
There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D. The database holds information on periodic tables, the discovery of the elements, the elucidation of atomic weights and the discovery of atomic structure (and much, much more).
| Year: 1808 | PT id = 5, Type = formulation data element weight structure |
Dalton's Elements
Two pages from John Dalton's A New System of Chemical Philosophy in which he proposed his version of atomic theory based on scientific experimentation (see the scanned book, page 219):
| Name | Modern Symbol | Dalton's Data | Modern Values | % error |
| Hydrog. | H | 1 | 1 | 0% |
| Azote | N | 5 | 14 | -180% |
| Carbone | C | 5 | 12 | -140% |
| Oxygen | O | 7 | 16 | -129% |
| Phosphorus | P | 9 | 31 | -244% |
| Sulphur | S | 13 | 32.1 | -147% |
| Magnesia | Mg | 20 | 24.3 | -22% |
| Lime | Ca | 24 | 40.1 | -67% |
| Soda | Na | 28 | 23 | 18% |
| Potash | K | 42 | 39.1 | 7% |
| Strontites | Sr | 46 | 87.6 | -90% |
| Barytes | Ba | 68 | 137.3 | -102% |
| Iron | Fe | 50 | 55.8 | -12% |
| Zinc | Zn | 56 | 65.4 | -17% |
| Copper | Cu | 56 | 63.5 | -13% |
| Lead | Pb | 90 | 200.6 | -123% |
| Silver | Ag | 190 | 107.9 | 43% |
| Gold | Au | 190 | 197 | -4% |
| Platina | Pt | 190 | 195.1 | -3% |
| Mercury | Hg | 167 | 200.6 | -20% |
- Dalton states that he is considering "chemical elements or ultimate particles"
- Dalton assigns hydrogen as having a relative weight of 1.
- Note the seemingly huge % errors in the atomic weights, compared with modern values.
- These errors occurred because while Dalton had deduced that atoms combine in fixed (stoichiometric) ratios in compounds, he not always know what the ratios were. Thus there were two unknowns: the atomic weights (masses) and the stoichiometric ratios.
By Mark Leach
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| What is the Periodic Table Showing? | Periodicity |
© Mark R. Leach Ph.D. 1999 –
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