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प्रश्न
What was the basis of the earliest attempts made for classification and grouping of elements?
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उत्तर
The basis of the earliest attempts for the classification of elements was the chemical and physical properties observed by the scientists. Some reactions with known elements and compounds were compared.
The atomic weights were used to order them. To group them into groups they tried to observe the periodicity of the properties as the atomic weight increases. Law of triads and then the law of octaves was proposed. Doberneiner, Chancourtois, and Newlands proposed these laws and prepared some tables.
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संबंधित प्रश्न
Write the electronic configuration of two elements X and Y whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element X reacts with element Y. Draw the electron-dot structure of the product and also state the nature of the bond formed between both the elements.
Why do we classify elements?
An element X is in group 2 of the periodic table What will be the formula of its chloride?
An element X combines with oxygen to form an oxide XO. This oxide is electrically conducting.
(a) How many electrons would be there in the outermost shell of the element X?
(b) To which group of the periodic tables does the element X belong?
(c) Write the formula of the compound formed when X reacts with chlorine.
Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electron shells but different number of electrons in their outermost shells. It was found that elements A and G combine to form an ionic compound. This ionic compound is added in a small amount to almost all vegetables and dishes during cooking. Oxides of elements A and B are basis in nature while those of elements E and F acidic. The oxide of element D is, however, almost neutral. Based on the above information, answer the following questions:
(a) To which group or period of the periodic table do these elements belong?
(b) What would be the nature of compound formed by a combination of elements B and F?
(c) Which two of these elements could definitely be metals?
(d) Which one of the eight elements is most likely to be found in gaseous state at room temperature?
(e) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write formula of the compound formed by the combination of C and G.
Give a reason why elements need to be properly classified.
Why was this basis of classification discarded for future classification of elements?
What is the atomic number of elements of period 3 and group 17 of the Periodic Table?
Identify the following:
An element in Period 1 which can be placed in both Group 1 and Group 17 of the Periodic Table.
Element 'X' forms an oxide with the formula X2O3 which is a solid with high melting point. ‘X’ would most likely be placed in the group of the Periodic Table as:
