Periodic Table of Elements - PubChem
https://pubchem.ncbi.nlm.nih.gov/periodic-table/
Why Arrange Elements in a Table? Seeing chemical elements arranged in the modern periodic table is as familiar as seeing a map of the world, but it was not always so obvious. The creator of the periodic table, Dmitri Mendeleev, in 1869 began collecting and sorting known properties of elements, like he was playing a game, while traveling by train. He noticed that there were groups of elements that exhibited similar properties, but he also noticed that there were plenty of exceptions to the ...
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