Periodic Table Discovered at Scotland's St Andrews University Could Be World's Oldest

Alan Aitken
Alan Aitken

The oldest surviving periodic table of elements in the world may have been found at the University of St Andrews in Scotland, according to the Scottish newspaper The Courier.

University researchers and international experts recently determined that the chart, which was rediscovered in a chemistry department storage area in 2014, dates back to 1885—just 16 years after Russian chemist Dmitri Mendeleev invented the method of sorting the elements into related groups and arranging them by increasing atomic weight.

Mendeleev’s original periodic table had 60 elements, while the modern version we use today contains 118 elements. The chart found at St Andrews is similar to Mendeleev’s second version of the table, created in 1871. It’s thought to be the only surviving table of its kind in Europe.

The periodic table soaks in a washing treatment
Richard Hawkes

The St Andrews table is written in German, and was presumably produced for German universities to use as a teaching aid, according to St Andrews chemistry professor David O’Hagan. The item itself was dated 1885, but St Andrews researcher M. Pilar Gil found a receipt showing that the university purchased the table from a German catalog in 1888. A St Andrews chemistry professor at the time likely ordered it because he wanted to have the latest teaching materials in the scientific field, even if they weren't written in English.

When university staffers first found the table in 2014, it was in “bad condition,” O’Hagan tells The Courier in the video below. The material was fragile and bits of it flaked off when it was handled. Conservators in the university's special collections department have since worked to preserve the document for posterity.

The 19th century table looks quite a bit different from its modern counterparts. Although Mendeleev laid the groundwork for the periodic table we know today, English physicist Henry Moseley improved it in 1913 by rearranging the elements by the number of protons they had rather than their atomic weight. Then, in the 1920s, Horace Deming created the boxy layout we now associate with periodic tables.

Learn more about the St Andrews discovery in the video below.

[h/t The Courier]

What Caused Pangea to Break Apart?

Emily Devenport:

There's another way to look at this question. People tend to think in terms of supercontinents forming and then breaking up again due to convection currents in the mantle, hot material rising and causing rifts in weaker spots, possibly in old sutures where the continents were shoved together—but what is really happening is that ocean basins are opening and closing, and the ocean has an active role in subduction.

The opening and closing of an ocean basin is called a Wilson Cycle. It begins when hot material rising from the mantle stretches the overlying crust. As molten material rises, a rift is formed. The rift is widened as material continues to squeeze into it. If that rifting goes on long enough, through a broad enough swath of a continent, ocean water will eventually flow into it, and an ocean basin begins to form. The upwelling of hot material will continue to rise through that thinner area of crust, pushing the plates apart. The Atlantic Ocean is an example of a basin that is well along in the Wilson Cycle; eventually subduction is going to begin at its margins, and the whole shebang will pivot.

This will happen because at the edge of continents, sediments accumulate. The weight of those sediments, combined with the weight of the water, drives the heavier, denser edge of the oceanic plate under the continental crust, which is fatter and lighter. Eventually subduction begins, and the basin begins to close again. The Pacific Ocean is an example of a basin that's closing.

If you look at a map of the oceanic rift zones, you'll notice that the one in the Atlantic is pretty much in the middle of that ocean, but the Pacific rift zone has been pulled all the way over to North America above Central America. Subduction is actively occurring on all margins of that plate.

The simple picture is that the continents are moving toward each other across the Pacific Ocean while the Atlantic Basin continues to widen. The truth is more complicated. When plates subduct, the water in the crust lowers the melting point of those rocks, so partial melting occurs. The partially melted material begins to rise through the overlying rocks, because it's less dense, and decompression melting occurs. Eventually, the upwelling of hot material forms plutons and volcanoes above the subduction zones. Fore-arc and Back-arc [PDF] basins can form. As the oceanic crust is pulled under the continental plate, island chains and other chunky bits get sutured to the edge of the continent along with sediments, making it larger. Our world is ~4.6 billion years old, so our continents are really large, now. They're unlikely to rift through the ancient cratons that formed their hearts.

What will happen if subduction begins on the eastern side of North America before the Pacific Basin closes? The margin next to California is a transform fault; it's not subducting. Will it eventually push itself under that part of North America again, or will the transform zone get bigger? The hot spot that was driving the ancient Farallon Plate under North America was eventually overridden by the southwestern states (Arizona, New Mexico, etc.) forming a rift zone. Will it continue to rift or poop out?

There are computer models predicting what supercontinent may form next. They will continue to change as our understanding of tectonic processes gets more accurate.

This post originally appeared on Quora. Click here to view.

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