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प्रश्न
What is modern periodic law?
उत्तर
Modern periodic law states that the physical and chemical properties of elements are a periodic function of their atomic numbers i.e., if the elements are arranged in the order of their atomic numbers, the elements with similar properties are repeated after definite regular intervals.
Concept Insight: The elements are characterized by their atomic number as well as atomic weight. Modern periodic law uses atomic number which is number of protons or number of electrons present in an atom of an element.
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संबंधित प्रश्न
The atomic masses of three elements A, B and C having similar chemical properties are 7, 23 and 39, respectively.
- Calculate the average atomic mass of elements A and C.
- Compare the average atomic mass with atomic mass of B.
- What could the elements A, B and C be?
Two elements ‘P’ and ‘Q’ belong to the same period of the modern periodic table and are in Group 1 and Group 2, respectively. Compare their following characteristics in tabular form:-
(a) The number of electrons in their atoms
(b) The sizes of their atoms
(c) Their metallic character
(d) Their tendencies to lose electrons
(e) The formula of their oxides
(f) The formula of their chlorides
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
Calculate the mass of Calcium that will contain the same number of the atom as are present in 3.2 gm of Sulphur.
[Atomic masses: S=32, Ca=40]
How does the number of valence electrons vary on moving from left or right in the second period of the periodic table?
On the basis of electronic configuration, how will you identify the first and the last element of a period?
Use the letters only written in the Periodic Table given below to answer the questions that follow:
(a) State the number of valence electrons in the atom J.(b) Which element shown forms ions with a single negative charge?
(c) Which Metallic element is more reactive than R?
(d) Which element has its electrons arranged in four shells?
The position of elements A, B, C, D and E in the periodic table are shown below:
|
Group 1 |
Group 2 |
Group 17 |
Group 18 |
|
|
|
|
D |
|
|
B |
C |
|
|
A |
|
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E |
State which is most reactive (i) metal (ii) non-metal
Fill in the blanks from the words A to F given below’.
A: Decreases
B: Increases
C: Remains same
D: Increases by one
E: Electropositive
F: Electronegative
Across a period from left to right in the Modern Periodic Table.
No. of electron shells _________; No. of valence electrons __________: Electronegativity increases Character of elements changes from electropositive to ________.
Match the option A and B with the statements (i) and (ii):
| A. metal | (i) The metal that forms two types of ion. |
| B. iron | (ii) An element with electronic configuration 2, 8, 8, 3. |
