jan 19, 1873 - Demitri Mendeleev(table)
Description:
Mendeleev said that the periodic pattern didn't apply to heavier elements. He decided to try to keep the pattern by saving spaces for elements that weren't discovered yet. He called the elements that were unknown at the time aluminium, silicon, and boron, and predicted their characteristics. He published a paper where he demonstrated all known elements on a single periodic table. .Added to timeline:
Date:
jan 19, 1873
Now
~ 152 years ago