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प्रश्न
Write a scientific reason.
There was ambiguity about the correct position of hydrogen in Mendeleev’s periodic table.
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उत्तर
- Hydrogen resembles alkali metals. It has one electron in its outermost shell like alkali metals. Its valency is 1 like alkali metals. It forms oxides (H2O) similar to alkali metals (Na2O). However, hydrogen also resembles halogens. It is a diatomic molecule (H2) like halogens (F2, Cl2). It is one electron deficient to achieve stable electronic configuration similar to halogens.
- Due to this unique behaviour of hydrogen, it could not be decided whether the correct position of hydrogen is in the group of alkali metals or in the group of halogens.
Thus, there was ambiguity about the correct position of hydrogen in Mendeleev's periodic table.
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संबंधित प्रश्न
Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic character of elements vary on moving down a vertical column? How does the size of atomic radius vary on moving left to right in a horizontal row? Give reason in support of your answer in the above two cases.
How many periods and groups are there in the long form of periodic table?
Explain why, the noble gases are placed in a separate group.
How do the atomic radii of elements change as we go from left to right in a period of the periodic table?
Explain why all the elements of a period have different chemical properties.
State how the valency of elements varies in a group of 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?
Consider the following elements:
20Ca, 8O, 18Ar, 16S, 4Be, 2He
Which of the above elements would you expect to be:
(i) very stable?
(ii) in group 2 of the periodic table?
(iii) in group 16 of the periodic table?
The elements A, B, C and D belong to groups 1, 2, 14 and 17 respectively of the periodic table. Which of the following pairs of elements would produce a covalent bond?
(i) A and D
(ii) C and D
(iii) A and B
(iv) B and C
(v) A and C
What are horizontal rows and vertical columns in a periodic table known as?
Name two elements in Alkali metals.
Name two elements in each case:
Transition element
Name the type of elements which have outermost shell complete.
What is the main characteristic of the last element in each period of the periodic table?
Fill in the blank:
The horizontal rows in the periodic table are called _____________.
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.
Write a short note.
Position of isotopes in the Mendeleev’s and the modern periodic table.
What would be the correct order if Zn, Fe, Al and Cu are arranged in increasing order of reactivity?
Give the symbol and valency of the following element and radical.
Sulphur [Sulphide]
Give the symbol and valency of the following element and radical.
Nitrogen [Nitride]
Give the symbol and valency of the following element and radical.
Nitrate
Give the symbol and valency of the following element and radical.
Bisulphite
State what is meant by the term chemical formula.
Which of the following statements about the Modern periodic table is correct?
Find the correlation:
Mendeleev’s periodic table : atomic mass : : Modern periodic table : _______
p-block is composed of groups 1 and 2.
What is the symbol of the element Tungsten?
Where would you locate the element with electronic configuration 2,8 in the Modern Periodic Table?
An element which is an essential constituent of all organic compounds belongs to
Three elements A, B and C have 3, 4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the Modern Periodic Table. Also, give their valencies.
Compare the radii of two species X and Y. Give reasons for your answer.
- X has 12 protons and 12 electrons
- Y has 12 protons and 10 electrons
Arrange the following elements in the increasing order of their metallic character
| Mg, | Ca, | K, | Ge, | Ga |
The maximum number of electrons that can be accommodated in s, p,d, and f subshells are ______.
Spot the error:
There are 5 periods and 17 groups in the modern periodic table.
An element has 2 electrons in its N shell.
Is it a metal or a non-metal?
Answer the following in respect of element \[\ce{_16^32S}\].
Give its formula with hydrogen.
