The periodic table was invented by chemist Dmitri Mendeleev to organize and compare elements and understand their relations with each other. Mendeleev created the periodic table between 1868 and 1870 while writing his book titled "The Principles of Chemistry." Initially, Mendeleev created the chart for his personal benefit, but others quickly discovered its value, leading to its immediate acceptance and use by fellow chemists upon publication.
Mendeleev devoted much of his time in the late 1860s and early 1870s to identifying and comparing elements. He frequently discovered new elements while performing experiments, but had no way of keeping track of his findings. Consequently, he began jotting down new elements on paper, but quickly realized that he needed a way to sort and organize them for easy future reference. Mendeleev began loosely organizing a chart, which grouped elements according to their atomic weights. As he plotted elements in horizontal rows on his chart, Mendeleev noticed a distinct pattern begin to appear, but only when he left blanks in the chart. According to the American Institute of Physics, the spaces in between elements in the horizontal rows made elements with like chemical properties appear in regular, predicable patterns in vertical columns on the periodic table.