The periodic table of risk elements
You know the periodic table of elements, even if you flunked your science courses! It is the large colorful and blocky table that hanged on every school’s classrooms before becoming yet another mobile app. The periodic table is one of the early and iconic achievements of science. It lists all the pure chemical elements found in nature, the building blocks of all possible material substances. Each block contains a set of numbers that unambiguously characterizes each element and a single or two letter abbreviation for each: H for Hydrogen, He for Helium and so forth, going on for over a hundred different elements. When the periodic table was discovered by Mendeleev (apparently in his dream!) it was an extraordinary realization that the physical world has an underlying order at the microscopic level. In his own words: