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Question
How did the early chemists classify elements?
Solution
Early chemists classified the elements on the bases of their properties, nature, character, valency, and whether they were metals or non-metals.
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RELATED QUESTIONS
Why do we classify elements?
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?
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?
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Identify the bond between H and F in the HF molecules.
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Which of the above elements would you expect to be in group 16 of the Periodic Table?
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Arranged elements into groups containing three elements each.
Relate the names of the following scientists with the statements given below.
Arranged elements in the increasing order of atomic mass.
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| Symbol | Atomic No | Electronic Configuration | |
| 1. | He | 2 | ______ |
| 2. | Ne | ______ | 2,8 |
| 3. | Ar | ______ | 2, 8,8 |
| 4. | Na | 11 | ______ |
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