READING 3.1.6 DMITRI MENDELEEV (1834-1907 CE) the PERIODIC TABLE Macquarie University Big History School: Core

READING 3.1.6 DMITRI MENDELEEV (1834-1907 CE) THE PERIODIC TABLE Macquarie University Big History School: Core

Lexile® measure: 1060L MACQUARIE UNIVERSITY BIG HISTORY SCHOOL: CORE - READING 3.1.6. DMITRI MENDELEEV: THE PERIODIC TABLE - 1060L 2

Threshold 3 is the creation of new chemical elements, largely thanks to stars. These created all the building blocks of which complexity is made on Earth and the wider Universe. Yet the nature of these new chemical elements wasn’t just random. DMITRI MENDELEEV (1834-1907 CE) THE PERIODIC TABLE By David Baker

Elements have laws just as fixed as the law of gravity. In the 19th century it was Russian scientist Dmitri Ivanovich Mendeleev (1834-1907 CE) who unravelled how the building blocks of the Universe behaved and interacted. He predicted the existence of elements and their traits even before they were discovered! And Mendeleev left humanity with a vital piece of knowledge – the periodic table, which still forms the backbone of chemistry today. Since ancient times, we’d known about elements such as gold, silver, tin, copper, lead, and mercury. Then in Hamburg in 1669, Hennig Brand discovered phosphorus. Over the next two centuries, more elements were discovered. Scientists put the elements on a list, ordered by how much each element weighed – their atomic mass. But from the lightest to the heaviest, there was no clear pattern that governed their properties. The light ones were different from each other, and the heavy ones were different from each other. This was a puzzle. In 1817, German chemist Johannes Dobereiner noticed that the elements in that list followed patterns. Elements with similar properties appeared in starts and jumps down the list. Calcium has similar traits to strontium and barium despite their having very different weights. The pattern down MACQUARIE UNIVERSITY BIG HISTORY SCHOOL: CORE - READING 3.1.6. DMITRI MENDELEEV: THE PERIODIC TABLE - 1060L 3

the list was periodic (defined as “appearing or occurring at intervals”). By 1860, about 56 elements had been discovered. In 1862 French geologist, de Chancourtois tried to show the periodic pattern in the atomic list. In 1864 John Newlands an English chemist figured out that similar traits occurred at periodic intervals of eight. But the pattern of similar traits occurring periodically every eight elements was not perfect. It failed the further you went down the old list. Was the periodic similarity of elemental traits in the early part of the periodic table just a coincidence? Enter Dmitri Ivanovich Mendeleev! He was born to a family in Siberia an academic family that had fallen on hard times. His father, Ivan, was an academic who died when Dimitri was 13. This left Dmitri’s mother, Maria, to support her large number of children. She came from the merchant class and was able to reopen an old glass factory, but it burned down a year later. Dmitri attended school in Siberia and showed a lot of potential. So when Dmitri was 15, his mother saddled up a horse and they rode hundreds and hundreds of kilometres across Siberia and through the Ural Mountains to Moscow where Maria pleaded with the university to let Dmitri study. They However, Lecoq de Boisbaudran measured the density of Gallium rejected him. So Maria and Dmitri rode all the way from Moscow to the to be lighter than Mendeleev had predicted. And so, without even university in St. Petersburg, his father’s old university, where Dmitri was seeing Gallium before, Mendeleev wrote him and told him that his accepted. Maria died shortly after her mission was complete. measurements were incorrect. Lecoq de Boisbaudran measured it again, Dmitri graduated, caught tuberculosis, and had to go to the Crimea to and Mendeleev’s prediction was 100% accurate. Such was the power of recuperate. While Dmitri was there, he gained a Masters degree at a Mendeleev’s periodic table! school in Simferopol. Dmitri returned to St. Petersburg in 1857 to start his Over the next 30 years, Mendeleev’s predictions were proven right again career as a scientist. and again as new elements were discovered. Mendeleev’s periodic table Ten years passed as Dmitri Mendeleev worked as a teacher and researcher. spread across the world and became the standard model for scientists. Mendeleev was familiar with the periodic nature of the traits of elements. Meanwhile, Mendeleev was given many awards and honours for his work. Yet he was distressed by the fact the pattern was imperfect. While He remained at the University of St. Petersburg until 1890 and held a job preparing a new textbook in 1867, Mendeleev concluded that the reason at the Bureau of Weights and Measures from 1893 until his death from why the pattern was not perfect is because there were elements that had illness in 1907. not been discovered yet! He inserted gaps in his periodic table where the By the time of his death, Mendeleev’s periodic table had enabled missing elements would be. He even predicted what the traits of those countless discoveries in chemistry in a magnificent example of collective missing elements would be. learning. And he had so changed the world of chemistry that in 1955 a Mendeleev published and presented his theory on numerous occasions newly discovered radioactive metallic element was named “Mendelevium” over the years, but many of his fellow chemists remained sceptical. Then after him. in 1875 French chemist Paul Emile Lecoq de Boisbaudran discovered Gallium – a soft metal that melted at low temperatures – exactly on the periodic table where Mendeleev predicted it would be. And Gallium possessed many of the traits Mendeleev predicted. MACQUARIE UNIVERSITY BIG HISTORY SCHOOL: CORE - READING 3.1.6. DMITRI MENDELEEV: THE PERIODIC TABLE - 1060L 4

REFERNCES Christian, David. Maps of Time: An Introduction to Big History. Berkeley: University of California Press, 2004. Christian, David and Cynthia Stokes Brown and Craig Benjamin. Big History: Between Nothing and Everything. New York: McGraw Hill, 2014. Gordin, Michael. A Well Ordered Thing: Dmitrii Mendeleev and the Shadow of the Periodic Table. New York: Basic Books, 2004. Mendeleev, Dmitri. “Remarks Concerning the Discovery of Gallium” in Mendeleev on the Periodic Law: Selected Writings, 1869-1905. ed. William Jensen. New York: Dover Publications, 2005.

IMAGE CREDITS ‘Dmitri Mendeleev at the Working Desk’ Credit: Nikolai Yaroshenko/Saint Petersburg State University, available at https://commons.wikimedia.org/wiki/File:MendeleevDI_ Jaroishenko_1886.jpg Public Domain Mark 1.0 (https://creativecommons.org/publicdomain/ mark/1.0/deed.en). ‘Mendeleev’s Table 5th II’ Credit: Dmitri Mendeleev/Ragesoss, https://commons.wikimedia. org/wiki/File:Mendeleev_Table_5th_II.jpg Public Domain Mark 1.0 (https://creativecommons. org/publicdomain/mark/1.0/deed.en). ‘The Soviet Union 1957 CPA 1978 Stamp (Dmitri Mendeleev)’ Credit: Fioshin, https://commons. wikimedia.org/wiki/File:The_Soviet_Union_1957_CPA_1978_stamp_(Dmitri_Mendeleev).jpg

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