1869 – The periodic table is formulated

1869 – The periodic table is formulated

As part of our 200 year celebrations we have been covering significant events from 1817 to now. Last week we took a little break from science in favour of spending some time in Wonderland, but this week we are firmly back on topic. The year is 1869 when the Periodic Table is formulated.

Despite being over a century in the making and that there are known to be a lot of contributors to the development of the Periodic Table, Dmitri Mendeleev is generally given all the credit as its creator.

The Periodic System – doesn’t quite sound right does it?

Originally known as The Periodic System, its creation was initially helped in 1860 by the publication of more accurate atomic weights.

Only 60 elements were known of at the time and some of the information about those 60 was inaccurate or incorrect so creating some sort of order for these was a challenge to say the least.

Mendeleev started by writing the elements on cards to catalogue them. Then one evening while playing patience he realised that the elements could be organised in a similar way in order of atomic weight.

By doing this he started to discover the mistakes that had been made when calculating some atomic masses and was able to recalculate these putting them in their correct position, for example, beryllium was given an atomic weight of 13.8 based on its valency being 3 which placed it between carbon and nitrogen, but there was no space. Mendeleev was able to recalculate it meaning its valency was 2 so it fitted perfectly between lithium and boron

Could Mendeleev see into the future?

Ok no, but what was really clever was that whilst building his system Mendeleev left spaces for elements that had not yet been discovered. During his lifetime more elements were discovered and therefore were added to the table in their designated space.

Sing along

So that is all well and good but the most important question is “Can you remember enough of the elements and their order to sing along…Ready? 1,2,3” https://www.youtube.com/watch?v=VgVQKCcfwnU

 

Authored by: Michael Meehan

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