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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
Rewrite the following statement after correction, if necessary:
Isotopes are the elements of the same group.
Why do we classify elements?
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.
A metal X is in the first group of the periodic table. What will be the formula of its oxide?
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?
Rearrange the columns 2 and 3 so as to match with the column 1.
| Column 1 | Column 2 | Column 3 |
| i. Triad | a. Lightest and negatively charged particle in all the atoms | 1. Mendeleev |
| ii. Octave | b. Concentrated mass and positive charge | 2. Thomson |
| iii. Atomic number | c. Average of the first and the third atomic mass | 3. Newlands |
| iv. Period | d. Properties of the eighth element similar to the first | 4. Rutherford |
| v. Nucleus | e. Positive charge on the nucleus | 5. Dobereiner |
| vi. Electron | f. Sequential change in molecular formulae | 6. Moseley |
The number of electrons in the outermost shell of alkali metals is ______.
Give a reason why elements need to be properly classified.
Write the name.
The atom having smallest atomic radius from group 1.
Complete the following table:
| Symbol | Atomic No | Electronic Configuration | |
| 1. | He | 2 | ______ |
| 2. | Ne | ______ | 2,8 |
| 3. | Ar | ______ | 2, 8,8 |
| 4. | Na | 11 | ______ |
