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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
An element X from group 2 reacts with element Y from group 16 of the periodic table.
(a) What is the formula of the compound formed?
(b) What is the nature of bond in the compound formed?
A metal X is in the first group of the periodic table. What will be the formula of its oxide?
An element X from group 2 of the periodic table reacts with an element Y from group 17 to form a compound.
(a) What is the nature of the compound formed?
(b) State whether the compound formed will conduct electricity or not.
(c) Give the formula of the compound formed.
(d) What is the valency of element X?
(e) How many electrons are there in the outermost shell of an atom of element Y?
The following diagram shows a part of the periodic table containing first three periods in which five elements have been represented by the letters a, b, c, d and e (which are not their chemical symbols):
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1 18 a 2 13 14 15 16 17 b c d e
(i) Select the letter which represents an alkali metal.
(ii) Select the letter which represents a nobles gas.
(iii) Select the letter which represents a halogen.
(iv) What type of bond is formed between a and e?
(v) What type of bond is formed between d and e?
In which block of the modern periodic table are the nonmetals found?
Why was this basis of classification discarded for future classification of elements?
Classify the following elements into Metals and Nonmetals.
S, Mg, Al, P, N, Na.
Which of the following hydroxides is most basic?
Complete the following triads by inserting the missing elements.
Cl, ______, I
Complete the following triads by inserting the missing elements.
Li, ______, K
