Mendeleev’s periodic table, published in 1869, was a vertical chart that organized 63 known elements by atomic weight. This arrangement placed elements with similar properties into horizontal rows.

The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

Two hundred years ago today, British chemist John Dalton helped turn chemistry into an exact science. He presented his Table of Atomic Weights at the Manchester Literary and Philosophical Society ...