Periodic Table Revisions

BillTre

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The Periodic Table is 150 years old sometime this year (I could not find its exact birthday).
Good job Mendeleev!
Here is a Science magazine news info graphic on how it has changed over time (before and after Mendeleev).
The graphic came out a while ago, but was not working then. Now it does.
 
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I think its because the periodic table evolved with our understanding of Chemistry and so there is no definitive date:

https://en.wikipedia.org/wiki/History_of_the_periodic_table

The article shows the many attempts at making a periodic table until we reach Mendeleev who published his first version on March 1, 1869. Later Moseley provided a better scheme of sorting the elements via atomic number and not atomic weight as Mendeleev had done.
 

robphy

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https://www.iypt2019.org/

Quote from
https://en.unesco.org/commemorations/iypt2019

International Year of the Periodic Table of Chemical Elements 2019
cover_iypt2019_shutterstock_chemical_elements.jpg

A yearlong initiative to raise awareness of chemistry and its applications for sustainable development.

The Periodic Table of Chemical Elements is one of the most significant achievements in science, capturing the essence not only of chemistry, but also of physics and biology. It is a unique tool, enabling scientist to predict the appearance and properties of matter on the Earth and in the rest of the Universe. The Periodic Table of Chemical Elements is more than just a guide or catalogue of the entire known atoms in the universe; it is essentially a window on the universe, helping to expand our understanding of the world around us. The year 2019 marks the 150th anniversary of its creation by Russian scientist Dmitry Ivanovich Mendeleev.

The Year was proclaimed by the United Nations General Assembly (A/RES/72/228(link is external)) and approved by UNESCO's General Conference (39C/ decision 60).
 

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