Periodic Table of Elements — Search & Detailed Data for All 118 Elements

Side Note — A Table Born from Blank Squares and Bold Predictions

In 1869, Russian chemist Dmitri Mendeleev arranged the 63 elements known at the time by atomic weight and noticed that their properties repeated in a periodic pattern. What made his table revolutionary wasn't just the classification — he deliberately left blank squares, predicting that undiscovered elements would eventually fill them. When gallium and germanium were later discovered, their properties matched his predictions almost perfectly, cementing the table's credibility.

Modern periodic tables are ordered by atomic number (proton count) rather than atomic weight. This became possible once the structure of the atomic nucleus was understood in the early 20th century, resolving exceptions like tellurium and iodine, whose atomic-weight order would otherwise break the periodicity of their chemical properties.

Element 113, nihonium, was the first new element credited to an Asian research team: RIKEN in Japan, following experiments conducted between 2004 and 2012. The table's blank squares aren't fully filled even today — the search for elements beyond 118, the hypothetical start of an eighth period, remains an active research topic at laboratories worldwide.