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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 X is in group 2 of the periodic table What will be the formula of its chloride?
An element A has an atomic number of 6. Another element B has 17 electrons in its one neutral atom.
(a) In which groups of the periodic table would you expect to find these elements?
(b) what type of bond is formed between A and B?
(c) Suggest a formula of the compound formed between A and B.
The elements A, B and C belong to groups 1, 14, and 17 respectively of the periodic table.
(a) Which two elements will form a covalent compound?
(b) Which two elements will form an ionic compound?
The elements Li, Na and K, each having one valence electron, are in period 2, 3 and 4 respectively of modern periodic table.
(i) In which group of the periodic table should they be ?
(ii) Which one of them is least reactive ?
(iii) Which one of them has the largest atomic radius ? Give reason in justify your answer in each case.
The elements A, B, and C belong to groups 1, 14, and 17 respectively of the Periodic Table. Which two elements will form ionic compounds?
An element X from group 2 of the Periodic Table reacts with Y from group 17 to form a compound. Give the formula of the compound.
Arrange the following elements in the order of their decreasing metallic character
Na, Si, Cl, Mg, Al
Complete the following cross word puzzle
Across:
(1) An element with atomic number 12.
(3) Metal used in making cans and member of Group 14.
(4) A lustrous non-metal which has 7 electrons in its outermost shell.
Down:
(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.
(5) The first element of second Period
(6) An element which is used in making fluorescent bulbs and is second member of Group 18 in the Modern Periodic Table
(7) A radioactive element which is the last member of halogen family.
(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.
(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests
Relate the names of the following scientists with the statements given below.
Arranged elements into groups containing three elements each.
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.
