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प्रश्न
Write a short note.
Position of isotopes in the Mendeleev’s and the modern periodic table.
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उत्तर
Isotopes: Isotopes are the atoms having the same atomic number but different atomic masses.
Therefore, according to Mendeleev’s classification, these should be placed at different places depending upon their atomic masses.
For example, hydrogen isotopes with atomic masses 1,2 and 3 should be placed at three places. However, isotopes have not been given separate places in the periodic table because of their similar properties. So this was a drawback of Mendeleev's periodic table as he could not explain the position of isotopes.
The modern periodic table is based upon the arrangement of the elements on the basis of their atomic number. So, all the isotopes of hydrogen should be placed at the same place depending upon their atomic number.
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संबंधित प्रश्न
Write the merits of the modern periodic table over Mendeleev’s Periodic table
Fill in the following blank with suitable word:
The horizontal rows in a periodic table are called ...............
How were the positions of isotopes of an element decided in the modern periodic table?
How were the positions of cobalt and nickel resolved in the modern periodic table?
On which side of the periodic table will you find non-metals?
Is it possible to have an element having atomic number 1.5 placed between hydrogen and helium?
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?
State whether the following statement is true or false:
On going down in a group of the periodic table, the number of valence electrons increases.
What is the major characteristic of the first elements in the periods of the periodic table? What is the general name of such elements?
Explain why All the elements of a group have similar chemical properties.
What is a period in a periodic table?
What is a group in the periodic table?
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?
From the standpoint of atomic structure, what determines which element will be the first and which the last in a period the periodic table?
Name the scientist who stated the modern periodic law.
Correct the statement.
Transition elements are placed at extreme right of the periodic table.
Name two elements in Alkaline earth metals.
Name two elements in halogens.
Name two elements in each case: Lanthanides
Name the type of elements which have one electron short of octet.
State the modern periodic law.
The horizontal rows in a periodic table are called _____.
Give the symbol and valency of the following element and radical.
Potassium
Give the chemical formula of sodium hydroxide
Give the chemical formula of sodium nitrate
State the number of elements in Period 2 of the Periodic Table.
State whether true or false. If false, correct the statement.
Lanthanides and actinides are kept at the bottom of the periodic table because they resemble each other but they do not resemble with any other group elements.
Which of the following statements about the Modern Periodic Table is correct:
Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?
Which of the following is the outermost shell for elements of period 2?
The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called as? Give one example of such a set of elements.
Arrange the following elements in the increasing order of their metallic character
| Mg, | Ca, | K, | Ge, | Ga |
An element with atomic number ______ will form a basic oxide.
Give reason for the following:
Inert gases do not form ion.
