National Periodic Table Day

7 February is National Periodic Table Day, but to understand the development of the periodic table, we must first understand the discovery of elements and the effect they had on science.

The elements known to ancient man were few and included gold, silver, copper, iron, lead, tin, mercury, sulphur and carbon. These were all known prior to the first century AD.

By 1809, there were 47 discovered elements including arsenic, antimony, phosphorous and zinc. In 1817, Johann Dobereiner registered one of the earliest attempts to organise the elements, by grouping them into groups of three, based on similar qualities. On 7 February 1863, an English chemist by the name of John Newlands published one of the first tables of elements. This table divided the 56 known elements into 11 groups, based on the Law of Octaves. This method suggested that any one element will have similar properties to elements eight places before and behind it on the table.

Newlands was the first scientist to detect a pattern to the properties of elements by arranging them according to increasing atomic weight. As a result, his table left room for new discoveries, predicting that in future newly discovered elements would complete the table. He predicted the discovery of Germanium correctly.

While parts of Newlands’s table had flaws, so did some of the later proposed tables. In 1869, chemist Dimitri Mendeleew published a paper on developing a periodic table arranging the elements based on atomic mass. By this time, only 60 of the more than 100 elements known today, had been discovered.

Some inaccuracies attributed to some of the elements were corrected by Mendeleev but he also made assumptions about others, causing elements to be placed incorrectly on the table. Mendeleev correctly predicted the discovery of five elements and their compounds. The discoveries throughout Scot William Ramsay’s career from 1892 to 1910, along with those made by John William Strutt, Morris Travers and Frederick Soddy led to the identification of the noble gases. Ramsay was awarded a Nobel Prize in 1904 for discovering five elements. Henry Moseley, an experimental physicist, contributed to the development of the modern periodic table when he discovered in 1913 that each element has a specific number of protons. As a result, four new chemical elements were later found, though not during his lifetime.

Since the early 20th century there have been very few significant changes to the periodic table. The 21st century is still young though, and some researchers have suggested new approaches to the periodic table while maintaining its integrity as one of the most valuable tools in the science of chemistry.

National Periodic Table Day was founded in 2016 with the goal of promoting the challenges that were overcome to develop the modern periodic table. David T Steineker – author, inventor and chemistry teacher, from Kentucky – was inspired by those challenges and took the initiative to celebrate National Periodic Table Day.

To celebrate today visit www.PeriodicTableDay.org for more information.

Use #NationalPeriodicTableDay on social media.

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