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Happy birthday Dimitri Mendeleev
Posted on Feb 9, 2018 by Safe Radiation
The International Atomic Energy Agency (IAEA) has released a post to acknowledge Dimitri Mendeleev’s contributions as an architect of the Periodic Table of Elements. He was born on 8 February 1834 in Tobolsk, Russia. His version of the periodic table was initially released as a formal presentation on 6 March 1869 and later in the same year published in a scientific journal Zeitschrift für Chemie.
See an extract below from the first journal publication of Dimitri’s periodic table. Radioactivity was formally discovered 27 years later in 1896 by Henry Becquerel. Hence it is not surprising that we do not find many primordial radioactive elements in Dimitri’s periodic table. However, uranium gets a mention. Those days the symbol for element uranium was Ur; it is U now. Interestingly, Dimitri assigned an atomic weight of only 116 to uranium which is about half of what we know it now. The reason for this difference will be interesting to further research.
Later, after the discovery of radioactivity, the radiation from uranium salts was named as Becquerel Rays. Many radioactive elements and isotopes were discovered in quick succession. Exactly one hundred years ago, on 9 February 1918, an article by Frederick Soddy appeared in the Scientific American, titled ‘The complexity of the chemical elements – II, electrical relations, radio-active and the nuclear theory’. This article correctly mentions that the lead (Pb) generated from the uranium and thorium has different atomic weights; 206 and 208 respectively. The progress was indeed rapid.
Above: The world’s first view of Mendeleev’s Periodic Table – an extract from Zeitschrift fϋr Chemie, 1869
Below: Some of Mendeleev’s original notes