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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
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?
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 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.
Why do all the elements of the same group have similar properties?
Write the merits of the modern periodic table over Mendeleev’s Periodic table
Fill in the following blank with suitable word:
The basis for modern periodic table is ...............
How many periods and groups are there in the long form of periodic table?
Give two example of group 17 elements.
What is the name of those elements which divide metals and non-metals in the periodic table?
The three elements having chemical symbols of Si, B and Ge are:
(a) all metals
(b) all non-metals
(c) all metalloids
(d) Si is metalloid, B is metal and Ge is non-metal
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
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?
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.
Name two elements in Alkali metals.
Name two elements in each case:
Actinides
Fill in the blank:
The horizontal rows in the periodic table are called _____________.
Name the noble gas with 3 shells.
State the modern periodic law.
Name the cation and the anion in the salt – calcium sulphate
Give the symbol and valency of the following element and radical.
Potassium
Give the symbol and valency of the following element and radical.
Bicarbonate
Give the symbol and valency of the following element and radical.
Nitrate
Give the symbol and valency of the following element and radical.
Sulphate
Give the chemical formula of calcium phosphate
The groups 1 and 2 constitute the ______ block.
Find the correlation:
Mendeleev’s periodic table : atomic mass : : Modern periodic table : _______
Find the correlation:
Group 13 to 18 : p block : : ______ : d block
Right or wrong sentence.
To the left of the zig-zag line in the periodic table are the metal elements.
Complete the following flow chart.
______ and ______ are called inner transition elements.
The arrangement of elements in the Modern Periodic Table is based on their ______.
The amount of energy released when one or more electrons is added to the neutral atom is ______
The longest period of the Modern Periodic Table is period.
What is the symbol of the element Tungsten?
If an element X is placed in group 14, what will be the formula and the nature of bonding of its chloride?
Group 16 elements are collectively called as ______.
An element belonging to 3d series of modern periodic table has spin magnetic moment = 5.92 B.M. in +3 oxidation state. The atomic number of elements are ______.
Define periods of modern periodic table.
State the group and period, of the element having three shells with three electrons in valence shell.
