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प्रश्न
Write a scientific reason.
Lithium and sodium are included in the same group in the periodic table.
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उत्तर
- Electronic configuration of lithium is (2, 1). The 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 the periodic table.
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संबंधित प्रश्न
Compare and contrast the arrangement of elements in Mendeleev’s periodic Table and the Modern Periodic Table.
How does the metallic character of elements in Modern Periodic Table vary on moving from left to right in a period, and (ii) down a group?Give reason to justify your answer.
How does the tendency of elements to gain electrons change as we move from left to right in a period? State the reason of this change.
What is meant by a period, in a periodic table?
Name the scientist who prepared modern periodic table.
The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of elements is:
(a) electron
(b) proton
(c) neutron
(d) meson
Which element has the electronic configuration 2, 8, 2?
What is the fundamental difference in the electron configurations between the group 1 and group 2 elements?
What is the main characteristic of the last elements in the periods of the periodic table? What is the general name of such elements?
In what respects do the properties of group 1 elements differ from those of group 17 elements? Explain with examples by taking one element from each group.
In the modern Periodic Table, why does cobalt with higher atomic mass of 58.93 appear before nickel having lower atomic mass of 58.71?
What are the groups in a periodic table? Give two characteristics of each.
Which of the following are the correct characteristics of isotopes of an element?
(i) same atomic mass
(ii) same atomic number
(iii) same physical properties
(iv) same chemical properties
(a) (i), (ii) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
How many groups and periods does the modern periodic table have?
What do you understand by typical elements?
How does the electronic configuration of an atom relate to its position in the modern periodic table?
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Is it larger or smaller than caesium (Cs)?
Name an alkali metal in period 3 and halogen in period 2.
State the main aim of classifying elements. Which is the more fundamental property of elements that is used in the development of Modern Periodic Table? Name and state the law based on this fundamental property. On which side of the periodic table one can find metals, non-metals and metalloids?
An element E has following electronic configuration:
|
K |
L |
M |
|
2 |
8 |
6 |
(a) To which group of the periodic table does element E belong?
(b) To which period of the periodic table does element E belong?
(c) State the number of valence electrons present in element E.
(d) State the valency of the element E.
How will the tendency to gain electrons change as we go from left to right across a period? Why?
What would be the correct order if Zn, Fe, Al and Cu are arranged in increasing order of reactivity?
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 the following characteristics in the tabular form.
- Number of electrons in their atoms
- Their tendency to lose electrons
- Their metallic characters
- Formation of their oxides
- Formulae of their chlorides
Name the cation and the anion in the salt – calcium sulphate
Give the chemical formula of sodium nitrate
Give the chemical formula of sodium sulphite
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Find the odd one out and give its explanation.
In the modern periodic table, the positions of 1 to 20 elements are shown here. Identify the elements A and B. Write their atomic number.
______ forms the basis of the modern periodic table.
The scientist who propounded the modern periodic law is ______.
______ and ______ are called inner transition elements.
The arrangement of elements in the Modern Periodic Table is based on their ______.
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An element has the atomic number 12.
- Write the electric configuration.
- To which group and period does it belong.
Define groups of modern periodic table.
Select the appropriate options and complete the following paragraph:
(metals, non-metals, metalloids, four, seven, s-block, p-block, d-block, f-block).
On the basis of electronic configuration, elements in the modern periodic table are classified Into ______ blocks. Groups 1 and 2 elements are included in ______ and all these elements are metals. (except Hydrogen). Group 13 to 18 elements are included in ______. This block contains metals, non-metals and metalloids. Group 3 to 12 elements are included in ______ and all the elements are ______ elements shown at the bottom of the periodic table i.e. Lanthanides and Actinides constitute ______ and all these elements are metals.
Match the atomic number with the following:
A rare gas.
