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प्रश्न
What is the need for classification of elements?
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उत्तर
It is impossible for a chemist to study all the elements and their compounds. Hence, classification is a must.
Following are the reasons for the classification of elements:
- To study elements better
- To correlate the properties of the elements with some fundamental properties which are characteristic of all the elements
- To reveal relationships between elements
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संबंधित प्रश्न
An element Y is in second period and group 16 of the periodic table:
(i) Is it a metal or non-metal?
(ii) What is the number of valence electrons in its atom?
(iii) What is its valency?
(iv) What is the name of the element?
(v) What will be the formula of the compound formed by Y with sodium?
An element A from group 14 of the periodic table combines with an element B from group 16.
(i) What type of chemical bond is formed?
(ii) Give the formula of the compound formed.
Write the names and symbols of two very reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure, how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.
A non-metal X which is the largest constituent of air combines with hydrogen when heated in the presence of iron as catalyst to form a gas Y. When gas Y is treated with sulphuric acid, it forms a compound Z which is used as a chemical fertiliser.
(a) What are X, Y and Z?
(b) To which group of periodic table does X belong?
(c) Name the periodic table in which X is placed.
(d) Which element is placed just before X in the period?
(e) Which element is placed just after X in the period?
Alkaline earth metals have valency 2. This means that their position in the modern periodic table is in ______.
(a) How is possible valency of an element determined from the electronic configuration of its atom ?
(b) Determine the valency of an element X whose atomic number is 15.
How did the early chemists classify elements?
The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was ______.
Which of the following property will be common in group 1 elements?
Complete the following triads by inserting the missing elements.
Cl, ______, I
