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प्रश्न
Why does the size of the atoms progressively become smaller when we move from sodium (Na) to chlorine (Cl) in the third period of the periodic table?
उत्तर
The size of atoms decreases progressively, on moving from sodium (Na) to chlorine (Cl) in the third period because the atomic number of the elements increases. Likewise, the number of electrons and protons in the atoms also increases. As the positive charges on the nucleus increase, the outermost electrons are held more tightly by the nucleus. Therefore, the size of the atom decreases.
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संबंधित प्रश्न
Given below are some elements of the modern periodic table. Atomic number of the element is given in parentheses.
A(4), B(9), C(14), D(19), E(20)
(a) Select the element that has one electron in the outermost shell. Also, write the electronic configuration of this element.
(b) Which two elements amongst these belong to the same group? Give reasons for your answer.
(c) Which two elements amongst these belong to the same period? Which one of the two has bigger atomic radius?
Write the number of horizontal rows in the modern periodic table. What are these rows called?
Write any one difference in the electronic configurations of group-1 and group-2 elements ?
Consider two elements 'X' (Atomic number 17) and 'Y' (Atomic number 20)
(i) Write the positions of these elements in the modern periodic table giving justification.
(ii) Write the formula of the compound formed by the combination of 'X' and 'Y'.
(iii) Draw the electron-dot structure of the compound formed and state the nature of the bond formed between the two elements ?
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)
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]
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?
How does the electropositive character of elements change on going down in a group of the periodic table?
In which part of a group would you separately expect the elements to have the greatest metallic character
In each of the following pair, choose the atom having the bigger size:
(a) Mg (At. No.12) or Cl (At. No.17)
State the valency of the elements of periods 3 and write the formula of their oxides.
How does the number of:
valence electrons and
Explain, the statement 'In each period, the atomic radii gradually decrease with increase in atomic number'. Give one example to justify your answer.
Select the correct answer
Number of shells in potassium are
Give the number of the group and the period of elements having three shells with three electrons in valence shell.
Arrange the following as per instruction given in the bracket
Na, K, Cl, S, Si (increasing ionisation potential)
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 |
|
|
E |
State which is most reactive (i) metal (ii) non-metal
An element A has 2 electrons in its fourth shell. State:
position in the periodic table
What is meant by a Group in the Periodic Table?
