Description of the Experience
Periodic table (PT) is thought in the context of general chemistry and general chemistry as it results from its name can be applied in every other area. Of course, students do not perceive it that way. In textbooks which are from 1985 is the most primitive form of PT and about each element there are only 2 information.
It is very difficult to force students into buying their own PT. I have one big PT in a classroom but it is necessary to have at least one PT in each table. Firstly I explain that areas which are marked in colour are not for periodic table to be nicer but they have exact meaning. In colour are marked metals, semi-metals and non-metals, 2 elements which are under normal conditions in liquid state – bromine and lead which is also metal. Totally different is hydrogen who has its own unique position.
Each PT has a legend which describes what every record means. If students have prepared for lessons and knew the basic information they would understood it also without my help, but they perceive it as something totally new.
63 chemical elements were known at the beginning of the 19th century. Some chemists tried to make some system in those elements, find some connections between them and what makes them different.
Only D.I.Mendelejev succeeded in 1869. He published the table in the magazine of Russian scientific chemic society, but not under the name as we now it but as a Try to make a system…
His father was a teacher and his family owned glassworks. His father got blind after some time so all the responsibilities were up to his mother. Although he had difficult conditions in his family, Mendelejev went to study at a university. He was not in a good health state. He was not friendly but he was married even though the marriage was not ideal.
After finishing his studies he wrote very important books in which he got a basis for chemistry. He dealt also with applied chemistry what was very unusual at that time, for example how to use chemical knowledge in cultivation of various crops. We need to understand also historical conditions which were in Russia at that time. Russia was interested in oil production, discovery of which was not noticed for some time and it was used only for kerosene production. He was one of the first people who tried to create some international system of units, whether in chemistry or physics.
In the first half of 19th century in global scientific society was different ambiance, there was a rivalry and his work about the system of elements was not accepted immediately. Its correctness was confirmed in 1875 when chemical elements which Mendelejev predicted to exist were discovered.
I consider this introduction as necessary because thanks to it will students at least partially understand the effort that was needed for someone to prove something. And Mendelejev did something really important because nothing has changed in his system, only new elements were added to it and states more facts about them.
I consider this experience to be positive.
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