How the periodic table went from a sketch to an enduring masterpiece

150 years ago, Mendeleev perceived the relationships of the chemical elements

In Danish physicist Niels Bohr’s 1922 version of the periodic table, adapted from a table by Danish chemist Julius Thomsen, elements with similar properties occupy horizontal rows connected by lines. The empty box on the right marks the expected occurrence of a group of elements that are chemically similar to the rare earth elements (numbers 58–70) in the preceding column.

Every field of science has its favorite anniversary.
For physics, it’s Newton’s Principia of 1687, the book that introduced the laws of motion and gravity. Biology celebrates Darwin’s On the Origin of Species (1859) along with his birthday (1809). Astronomy fans commemorate 1543, when Copernicus placed the sun at the center of the solar system.
And for chemistry, no cause for celebration surpasses the origin of the periodic table of the elements, created 150 years ago this March by the Russian chemist Dmitrii Ivanovich Mendeleev…


Ultrafast Chemistry in Motion

This video describes how the Linac Coherent Light Source, an X-ray free-electron laser at SLAC National Accelerator Laboratory, provided the first direct measurements of how a ring-shaped gas molecule unravels in the millionths of a billionth of a second after it is split open by light. The measurements were compiled in sequence to form the basis for computer animations showing molecular motion. (SLAC National Accelerator Laboratory) ….
…..