From the National Center for Biotechnology Information/National Library of Medicine:
NCBI and PubChem are celebrating the 150th anniversary of the periodic table of chemical elements, one of the most recognized tools in science. The scientific community has declared 2019 to be “The International Year of the Periodic Table”.
We’re celebrating by launching the PubChem Periodic Table and Element pages, where you can find chemical element data and data sources. There’s always more to learn, so check out the PubChem blog for more about this incredible old resource.