Scientific Research

Periodic Table 150

2019 marks 150 years since the Periodic Table was created in 1869. This easily recognisable chart, which displays and orders every known chemical element, has become a stable reference point in the world of Science, particularly Chemistry.

It is the Russian scientist, Dmitri Mendeleev who is credited with the creation of the table. However, when he first put together his chart showing the elements, it looked rather different to the one we have today. As Science News reminds us, ‘When Dmitrii Mendeleev proposed his periodic table 150 years ago, no one knew what was inside an atom. Today, we know that an element’s place on the table, along with its chemical properties, has a lot to do with the element’s proton number as well as how its electrons are configured.’

Born in 1834, Mendeleev was part of a large Siberian family. After the death of his father, Dmitri’s mother transported her family over 1500 miles to St. Petersburg. Once there she saved enough to allow her son to go to school, where his advanced intellect quickly became clear. By the time he was an adult, he was already a brilliant scientist. Mendeleev famously wrote a textbook, Chemical Principles, because he couldn’t find a decent book on Chemistry that was written in Russian.

There had been other scientists who had come close to creating a workable table of the chemical elements before Mendeleev. The earliest attempt to classify them was in 1789, when French scientist, Antoine Lavoisier, grouped them based on their properties; into gases, non-metals, metals and earths. However, it was Mendeleev who finally managed to arrange them into an order that worked.

His discovery came when, in February 1869, he was writing the properties of the elements on pieces of card and arranging and rearranging until, as a spokesman for the Royal Society of Chemistry explains, “he realised that, by putting them in order of increasing atomic weight, certain types of element regularly occurred. For example, a reactive non-metal was directly followed by a very reactive light metal and then a less reactive light metal. Initially, the table had similar elements in horizontal rows, but he soon changed them to fit in vertical columns, as we see today.”

One of the reasons Mendeleev’s work was so groundbreaking was that he was forward-thinking enough to leave spaces within the table, with a mind to the chemical element discoveries of the future.

Scientific advancements and discoveries since have indeed meant that the Periodic Table has gradually accumulated and added many new elements. Four new elements were added in 2016 alone.

Although Mendeleev never received a Nobel Prize for his work, the 101st element to be discovered was named Mendelevium after him. 2019 has been declared the “International Year of the Periodic Table of Chemical Elements (IYPT2019)” by the United Nations General Assembly and UNESCO. For information about the activities taking place across the UK and the world as a whole, you can find out more, visit-

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Dr Kathryn Bates is a graduate of archaeology and history. She has excavated across the world as an archaeologist, and tutored medieval history at Leicester University. She joined the administrative team at Oxford Open Learning twelve years ago. Alongside her distance learning work, Dr Bates is a bestselling novelist, and an itinerant creative writing tutor for primary school children.

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