Saturday, August 5, 2017

Who was the greatest theoretical chemist of the 19th century?

Dimitri Mendeleev, who proposed the periodic table of the elements, purely from phenomenology and without quantum mechanics!
He even successfully predicted the existence of new elements and their properties.

A friend who is a high school teacher [but not a scientist] asked me about how he should teach the periodic table to chemistry students. It is something that students often memorise, especially in rote-learning cultures, but have little idea about what it means and represents. It makes logical sense, even without quantum mechanics. This video nicely captures both how brilliant Mendeleev was and the logic behind the table.

A key idea is how each column contains elements with similar chemical and physical properties and that as one goes down the column there are systematic trends.
It is good for students to see this with their own eyes.
This video from the Royal Society of Chemistry shows in spectacular fashion how the alkali metals are all highly reactive and that as one goes down the column the reactivity increases.

The next amazing part of the story is how once quantum theory came along it all started to make sense!


  1. Good post to remind all about intuition in the age writing funding proposals for doing repetitive work. Prof Dan Singletons Chem Prof Texas A&M quote is valid for your posting
    Dan Singleton‏ @dasingleton Apr 19
    "Do not underestimate the old-timers of science. They had intuition. We have calculations. We are diminished"

  2. Off-topic: I think you might be interested in this paper:

    as it is consistent with statements you have made here before.

    1. Thanks.
      I am glad that paper finally got published. I had blogged about it last year.