What was Dobereiner’s basis,of classification of elements. It did not serve the purpose of classification.Certain elements resembled metallic as well as non-metallic both.Some characteristics being considered, varied under different conditions.Why was this basis of classification discarded for future classification of elements.Įarly chemists classified the elements on the bases on their properties, nature, character, valency and whether they were metals or non-metals. How did the early chemists classify elements. To help to define the relationship of one element with others.To help and correlate the properties of elements with the fundamental properties of different states of matter.It makes the study of elements in an organized manner.Give a reason why elements need to be properly classified.Įlements : “Are pure substances made up of one kind of atoms and cannot be broken down into simpler substances.” 118 elements are there. ( New Simplified Chemistry Dalal Class-9 ) Question 1. Groups : “The verticle columns from top to bottom are called groups.” Question 2.(2002)Īdditional Questions of-The Periodic Table What is meant by a Group in the Periodic Table. The similarities in the properties of a group of elements is because they have the same electronic configuration. The similarities in the properties of a group of elements is because they have the same _ (electronic configuration, number of outer electrons, atomic numbers.) Supply the missing word from those in brackets: If an element has one electron in its outermost energy level then it is likely to be metallic.Ĭopy and complete the following sentences choosing the correct word or words from those given in bracket at the end of each sentence : Supply the missing word from those in brackets: If an element has one electron in its outermost energy level then it is likely to be.
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