![]() In 1829, Johann Döbereiner recognised triads of elements with chemically similar properties, such as lithium, sodium and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two. Several other attempts were made to group elements together over the coming decades. The earliest attempt to classify the elements was in 1789, when Antoine Lavoisier grouped the elements based on their properties into gases, non-metals, metals and earths. Certainly Mendeleev was the first to publish a version of the table that we would recognise today, but does he deserve all the credit?Ī number of other chemists before Mendeleev were investigating patterns in the properties of the elements that were known at the time. Ask most chemists who discovered the periodic table and you will almost certainly get the answer Dmitri Mendeleev. #Who arranged the elements according to atomic mass downloadWe hope you enjoyed studying this lesson and learned something cool about Mendeleev's Periodic Table! Join our Discord community to get any questions you may have answered and to engage with other students just like you! Don't forget to download our app to experience our fun VR classrooms - we promise it makes studying much more fun! □. He failed to assign the position of the hydrogen atom, and also, the isotopes which were discovered later couldn't fit in the periodic table. What were the demerits of Mendeleev's periodic table? Gallium, which was discovered later, had properties similar to that predicted for Eka- aluminum.ģ. Eka- aluminum, as predicted by Mendeleev turned out to be which element? What was the basis of Mendeleev's periodic table?Įlements were arranged together with similar properties and in order of increasing atomic masses.Ģ. He failed to assign the position of the hydrogen atom, and the isotopes discovered later couldn't fit in the periodic table.ġ. He predicted some elements that were yet to be discovered and their properties too.Elements with similar properties were placed in the same group and arranged to increase atomic masses.Mendeleev had proposed a periodic table based on the mass number and properties of elements.He didn't give the total number of elements that were to be predicted.Isotopes of elements that were discovered later couldn't fit in Mendeleev's periodic table.The position of Hydrogen could not be decided as its properties were similar to group Ⅰ as well as group Ⅶ elements.Also, the new elements could be fitted in the periodic table proposed by Mendeleev without disturbing the place of existing elements. The gaps that he had left were fitted exactly by the new elements that were discovered in the later years. Source MERITS OF MENDELEEV'S PERIODIC TABLE: The interesting fact is that the properties predicted by Mendeleev were quite similar to the actual properties of elements: Gallium and Germanium. After several years, gallium was discovered, which took the place of eka-aluminum, and germanium took the place of eka-silicon. He had made a gap under the element aluminum and named it eka-aluminum, and the element under silicon was named eka-silicon. He made gaps for elements that were undiscovered at that time and predicted their properties too. But the primary aim was to arrange in order of similar properties. The main goal of Mendeleev was to group together elements in 'groups' by arranging them according to their atomic masses and properties. While group Ⅶ elements such as fluorine(F), chlorine(Cl), bromine(I) and iodine(I) were placed together as they form compounds with Hydrogen, i.e. For example, in group Ⅰ, hydrogen (H), lithium (Li), sodium (Na) and rubidium (Rb) were placed together as they formed oxides with the same chemical formula. The groups in the table were divided on the basis of H and O required by the elements to form compounds. He arranged the cards in various sequences but found out that the properties repeated when he arranged according to increased masses of elements. So, he took 63 cards and wrote one element on each one of them along with the atomic mass and properties known at that time. Mendeleev realized that atomic mass and properties of elements were interlinked. He arranged elements based on atomic mass and their chemical properties. In 1869, a Russian chemist Dmitri Mendeleev thought of organizing the then known 63 elements. Let’s take a crash course about the periodic table. Imagine what the scientists would have felt when there were too many elements! Let's see how they managed to sort out the huge number of elements. Won't you feel anxious in this huge mess of clothes? Imagine you are in a room with clothes lying on the floor, on the chair in short, all you can see are clothes everywhere. ![]()
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