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प्रश्न
Write scientific reason.
Lithium and sodium are included in the same group in periodic table.
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उत्तर
- Electronic configuration of lithium is (2, 1). Electronic configuration of sodium is (2, 8, 1).
- Both lithium and sodium have single electron in their outermost shell.
- Their valency is 1.
- In the periodic table, elements belonging to the same group have the same valency. Hence, lithium and sodium are included in the same group in periodic table.
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संबंधित प्रश्न
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
Compare and contrast the arrangement of elements in Mendeleev’s periodic Table and the Modern Periodic Table.
State modern periodic law.
What is meant by a period, in a periodic table?
Give two example of group 1 elements.
Give two example of group 18 elements.
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On the basis of electronic configuration, how will you identify the first element of a period?
Explain why, the first period of the periodic table has only two elements whereas second period has eight elements
(b) What is the number of elements is 3rd period, the modern periodic table?
The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers. (The letters given here not the chemical symbols of the elements):
| a 3 |
b 4 |
c 5 |
d 6 |
e 7 |
f 8 |
g 9 |
h 10 |
|
| i 11 |
j 12 |
k 13 |
l 14 |
m 15 |
n 16 |
o 17 |
p 18 |
(i) Which element has a bigger atom, a or f?
(ii) Which element has a higher valency, k or o?
(iii) Which element is more metallic i or k?
(iv) Which element is more non-metallic, d or g?
(v) Select a latter which represents a metal of valency 2.
(vi) Select a letter which represents a non-metal of valency 2.
Correct the statement.
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Name two elements in halogens.
Name two elements in each case:
Actinides
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State the modern periodic law.
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Give the symbol and valency of the following element and radical.
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Give the symbol and valency of the following element and radical.
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State the number of elements in Period 3 of the Periodic Table.
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Group 1 and 2 : s block : : group 13 and 18 : _______
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The longest period of the Modern Periodic Table is period.
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Spot the error:
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A part of modern periodic table is given below. On its basis, answer the following questions:
| Group No. → | 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 |
| Period ↓ | ||||||||
| 2 | A | B | ||||||
| 3 | E | D | F | C |
Write the molecular formula of the compound formed by the combination:
E and B
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Boron, Aluminium, Gallium, Indium, Thallium
Answer the following question in relation to the above group of elements:
If the electronic configuration of aluminium is 2, 8, 3, how many electrons are there in the outer shell of thallium?
