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Every year, it seems, we hear about anniversaries, some obscure and some more significant. But 2019 is big!! It is the 150th anniversary of a major step forward in our understanding of the chemical elements. In March 1869, Dimitri Mendeleev, an obscure Russian scientist, managed to explain chemistry in a way that made sense. Thus, UNESCO has designated the year 2019 as the Year of the Periodic Table of the elements. Some people consider that this single document is one of the most powerful icons in science.

That it should be so useful and relevant after so long a period, is no small achievement. Mostly scientific explanations come and go. In the case of Mendeleev’s document however, one commentator declared: “But despite the dramatic changes that have taken place in science over the past century – namely, the development of theories of relativity and quantum mechanics – there has been no revolution in the basic nature of the periodic system…. Remarkably, the periodic table is thus notable both for its historical roots and for its modern relevance.” (Eric Scerri. 2011. Scientific American January 21)

What is all the fuss about? And why do we care? Naturally Mendeleev’s ideas were based on the achievements of others down through the years. Robert Boyle (1627-1691), the fourteenth child of an Irish aristocrat, established chemistry as a science and he developed a definition of an element. Boyle proposed that substances were made up of different elements (consisting of tiny particles which we call atoms) and that these elements could be identified by conducting experiments. He suggested that elements could be combined to make compounds, and compounds could be separated back into their elements. These ideas were a big departure from the alchemists who believed that fire, water, earth and air constituted the foundational elements.

The next big leap in our understanding came from Russia. Demitri Mendeleev (1834-1907) was born in Siberia, the youngest of fourteen children (like Robert Boyle). Mendeleev’s father died when he was young, but his mother was determined that Demitri would be trained in science. She soon died too, but she urged him to “search for divine and scientific truth.” (Gordon Woods. 2007. education in chemistry  March 1) Whether her son was so motivated, is uncertain, but he never doubted that there had to be a logical explanation for the nature of the chemical elements, and that this relationship could not be the result of chance. (Mike Sutton. 2019. Chemistry World January 2)

The expectation that the chemical elements can be expected to react in orderly patterns, may seem obvious to us today, but actually that expectation is based on our understanding of who God is. As Kurt Wise declared in Faith, Form and Time (2002) p. 35: “If the physical world did not exist or did not have a consistent pattern that makes it understandable to humans or did not have consistent rules in space and time – or contained no truth at all – studying the physical world would be a futile exercise.”  It is the Biblical portrait of God who is rational and not capricious, that gives us the expectation similarly that nature will also display logical patterns (because God made it).

So let us return to the work of Mendeleev to see what he achieved and why. His academic progress was long and hard. However, in 1858 he was awarded a scholarship to study  in Heidelberg under Robert Bunsen. There he learned some highly significant skills. Specifically, he learned new techniques in spectroscopy and, as a result, he began to accumulate of lot of information about substances.

Bunsen and colleague Gustav Kirchhoff had improved on the technique called spectroscopy. This procedure involved burning a substance and splitting the resulting light by means of a prism. (When one splits sunlight, for example, one obtains a rainbow of colours.) These men improved the system into a procedure which yielded detailed patterns of the split light (spectrum). They discovered that every element has a unique spectral pattern of separate coloured lines. Thus, they established the technique of analytical spectroscopy which many, including Mendeleev, began to apply.

In 1867 Mendeleev was appointed as professor of inorganic chemistry at St. Petersburg  University. Lacking a suitable textbook in Russian, he set out to write his own. Now there is nothing like having to teach something that forces one to think clearly about the issue. Mendeleev had a lot of data concerning elements, but he could not explain what the relationships were. He wrote his information for each element on a separate card and he began to play around with arrangements of the cards. At a conference in 1860, Mendeleev heard Italian chemist Stanislao Cannizzaro present a major paper on atomic weights. Mendeleev incorporated this information on his cards for the elements.

We know now that atomic weights consist of the number of positively charged particles (protons) in the nucleus and the number of neutrons (similar particles but with no electrical charge). It is the number of protons (atomic number) which determines the chemical properties of an element. Nobody then knew any of that, but the atomic weight could be measured, and it was close enough to the atomic number to yield reasonable patterns.  These patterns are what Mendeleev and many others were seeking.

In early 1869 Mendeleev laid out his cards in vertical columns of elements with similar properties and increasing atomic weight. Different properties called for a new column. There were no elements with the same atomic weight. If the measured atomic weight did not fit an element into a group with similar properties, he adjusted his data to make the element fit the desired pattern (assuming that piece of information was wrong, which it was.) He also left gaps for elements not yet discovered which should fall into the pattern of properties and weights.

On March 6, 1869 Mendeleev’s paper was read on his behalf to the Russian Chemical Society. Few people, outside Russia, paid much attention.  Mendeleev called an improved version, printed in 1871, the Periodic Table. Then in 1875 a French chemist published a description of gallium, a new element. Mendeleev had predicted the existence of just such an element with those very properties. After this, chemists began to use Mendeleev’s table in their own studies. The data in the table helped them understand their observations. The amazing thing is that the orderly pattern that Mendeleev discerned, is as relevant today as when he first proposed it. However, we now understand why Mendeleev’s pattern works, thanks to enhanced understanding of the structure of the atom.

Why mere matter in its nature and interactions should reflect such logical patterns very much makes sense from a Christian worldview. It makes sense that our Creator God established the elegant relationships that Mendeleev elucidated. It does not make sense that they could have developed spontaneously. Who set the rules by which matter operates? An amazing mind of course.

So yes, let’s celebrate the sesquicentennial of the periodic table. And be sure to congratulate your chemist friends who continue to benefit from Mendeleev’s epic analysis.

For the rest of the story, see: https://crev.info/2019/02/design-in-chemistry-explained-by-a-phd-chemist/

Margaret Helder
April 2019

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