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प्रश्न
Give a reason for the following:
A transition from metallic to non-metallic elements is seen on moving from left to right in a period of the periodic table.
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उत्तर
In a period valence electrons increase from 1 to 7. But the shell remains the same. The element having valence electron 1, 2, 3 loose electrons, and are metals on the left. And elements having 5, 6, 7 valence electrons gain electrons and become non – metals are on the right of the periodic table.
Hence the transition from metallic to non-metallic character is seen from left to right a period.
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संबंधित प्रश्न
Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.
How do the valency and the atomic size of the elements vary while going from left to right along a period in the modern periodic table?
The following table shows the electronic configuration of the elements W, X, Y, Z:
| Element | w | x | y | z |
| Electronic configurations |
2, 8, 1 | 2, 8, 7 | 2, 5 | 1 |
Answer the following questions based on the table above:
1) What type of Bond is formed between :
a) W and X
b) Y and Z
2) What is the formula of the compound formed between :
a) X and Z
b) W and X
On moving from left to right in a period of the periodic table, the atomic number of elements increases. What happens to the size of atoms of elements on moving from left to right in a period?
(a) increases
(b) decreases
(c) remain the same
(d) first increases then decreases
What is its atomic number?
State the valency of the elements of periods 3 and write the formula of their oxides.
In the following table, the positions of six elements A, B, C, D, E and F are given as they are in the Modern Periodic Table :
 |
1 | 2 | 3-12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 2 | A | B | C | D | |||||
| 3 | E | F |
On the basis of the above table, answer the following questions :
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of B and C, whose atomic radius is bigger and why ?
(v) Write the common name for the family to which the elements D and F belong.
Give the number of the group and the period of elements having three shells with three electrons in valence shell.
Arrange the following as per instruction given in the bracket.
Li, K, Na, H ( decreasing order of their potential ionisation )
State the property trends in general of elements on moving down in a group of the periodic table.
