February 7 is National Periodic Table Day, when we celebrate the efforts of scientists over the centuries to figure out how different elements ...
The modern periodic table, arranged in rows and columns, was first introduced by Dmitri Mendeleev in 1869. At the time, it included the known elements and their properties, but Mendeleev predicted ...
Joel Achenbach writes about science and politics for The Washington Post's National desk. He has been a staff writer for The Post since 1990. He started the newsroom’s first online column, Rough ...
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