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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
The element which can from an acidic oxide should be the one whose atomic number is:
(a) 6
(b) 16
(c) 12
(d) 19
The element which forms a basis oxide has the atomic number of:
(a) 18
(b) 17
(c) 14
(d) 19
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):
-
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?
Give a reason why elements need to be properly classified.
Moseley’s periodic table is based on atomic mass.
What is the atomic number of elements of period 3 and group 17 of the Periodic Table?
Which one of the following statements is not correct about the trends in the properties of the elements of a period on going from left to right?
An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
- Identify the element
- Write the electronic configuration
- Write the balanced equation when it burns in the presence of air
- Write a balanced equation when this oxide is dissolved in water
- Draw the electron dot structure for the formation of this oxide
The atomic number of an element 'X' is 11.
- Write the electronic configuration of X and find its valency.
- Write the formula and nature of its oxide.
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:
-
- Na
- Mg
- Al
- Si
- Justify your answer in the above question (1).
