How Mendeleev’s Dream Helped Him Invent the Periodic Table

<p>The dream showed him a pattern that he had not noticed before: when the elements were ordered by increasing atomic weight, their properties repeated periodically. He realized that this was a natural law that governed the behavior of the elements. He also&nbsp;<em>left</em>&nbsp;some gaps in his table, predicting that new elements would be discovered to fill them. He even predicted some of their properties based on the patterns he observed.</p> <p><img alt="" src="https://miro.medium.com/v2/resize:fit:700/1*In8DoIdQk1XmUUM-n8ao5w.jpeg" style="height:1011px; width:700px" /></p> <p>Handwritten manuscript of the arrangement of elements written by Mendeleev, ca. 1869. Public domain image.&nbsp;<a href="https://commons.wikimedia.org/wiki/File:Mendeleev_law.jpg" rel="noopener ugc nofollow" target="_blank">Wikimedia Commons</a>.</p> <p>Mendeleev&rsquo;s dream was not a random occurrence, but a result of his subconscious mind working on the problem that he had been trying to solve for a long time. His dream was based on his previous knowledge and observations of the elements, but it also revealed something new and unexpected.</p> <p><a href="https://medium.com/physics-in-history/how-mendeleevs-dream-helped-him-invent-the-periodic-table-086571966ec2"><strong>Website</strong></a></p> <p>&nbsp;</p>