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प्रश्न
Taking into consideration the period of the elements given below, answer the following questions:
| Elements | Atomic Radius (pm) |
| O | 66 |
| B | 88 |
| C | 77 |
| N | 74 |
| Be | 111 |
| Li | 152 |
- Arrange the above elements in decreasing order of their atomic radii.
- State the period to which the above elements belong.
- Why this arrangement of elements is similar to the above period of modern periodic table?
- Which of the above elements have the biggest and the smallest atom?
- What is the periodic trend observed in the variation of atomic radius while going from left to right within a period?
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उत्तर
- Li > Be > B > C > N > O
- 2nd period
- Yes, this elemental arrangement resembles the era of the contemporary periodic table mentioned above. The positive charge on the nucleus grows one unit at a time as we move from left to right over a period of time, but when electrons are added to the same orbit, the pull away from the nucleus increases, reducing the size of the atom.
- Li is the biggest atom oxygen is the smallest atom
- While going from left to right within a period atomic radius decreases due to an increase in effective nuclear charge.
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संबंधित प्रश्न
An element 'X' belong to 3rd period and group 13 of the Modern Periodic Table.
(a) Determine the valence electrons and the valency of 'X'.
(b) Molecular formula of the compound formed when 'X' reacts with an element 'Y' (atomic number = 8).
(c) Write the name and formula of the compound formed when 'X' combines with chlorine
The elements 4Be, 12Mg and 20Ca, each having two valence electrons in their valence shells, are in periods 2, 3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case:
(a) In which group should they be?
(b) Which one of them is least reactive?
(c) Which one of them has the largest atomic size?
How do the atomic size and metallic character of elements vary as we move :-
(a) down a group and
(b) from left to right in a period
Write the number of vertical columns in the modern periodic table. What are these columns called?
Consider two elements 'A' (Atomic number 17) and 'B' (Atomic number 19) :
(i) Write the positions of these elements in the modern periodic table giving justification.
(ii) Write the formula of the compound formed when 'A' combines with 'B.'
(iii) Draw the electron dot structure of the compound and state the nature of the bond formed between the two 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 ?
Which element has the electronic configuration 2, 8, 2?
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
Differentiate between Normal elements and Transition elements.
How does the number of valence electrons vary on moving from left or right in the second period of the periodic table?
How does the valency of elements change of moving from left to right in the third period of the periodic table?
Rewrite the following statement after correction, if necessary:
The metallic character of elements in a period increases gradually on moving from left to right.
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?
For each of the following triads, name the element with the characteristics specified below:
| Elements | Least atomic radius | Chemically least reactive |
| (i) F, Cl, Br (ii) Li, Na, K |
.................... .................... |
.................... .................... |
Which of the following is the valence shell for the elements of second period of the modern periodic table?
(a) M shell
(b) K shell
(c) L shell
(d) N shell
The correct increasing order of the atomic radii of the elements oxygen, fluorine and nitrogen is:
(a) O, F, N
(b) N, F, O
(c) O, N, F
(d) F, O, N
In each of the following pair, choose the atom having the bigger size:
(a) Mg (At. No.12) or Cl (At. No.17)
What do you understand by periodicity?
Name the element which has the electronic configuration 2, 8, 3?
What is the common feature of the electronic configuration of the elements at the end of period 2, and period 3?
Four elements P, Q, R and S belong to the third period of the Modern Periodic Table and have respectively 1, 3, 5 and 7 electrons in their outermost shells. Write the electronic configurations of Q and R and determine their valences. Write the molecular formula of the compound formed when P and S combine.
Calculate the valency of element X whose atomic number is 9.
Atomic number of metal ‚A‛ is 11, while atomic number of metal ‚B‛ is 20. Which of them will be more reactive? Write the chemical reaction of dilute HCl with metal ‚A‛.
What is modern periodic law?
State the number of elements in period 1, period 2 and period 3 of the periodic table.
What is meant by a group in the periodic table?
The following questions refer to the Periodic Table.
What is the common feature of the electronic configurations of the elements in group 7?
Choose the correct answer from the choice given:
An element A belonging to Period 3 and Group II will have
An element Z has atomic number 16. Answer the following
(a) State the period and group to which Z belongs
(b) Is Z a metal or a non-metal?
(c) State the formula between Z and hydrogen.
(d) what kind of a compund is this?
Choose the word or phrase from the bracket which correctly complete each of the following statement:
Metals are good ................. (oxidising agents/reducing agents) because they are electron ............. (acceptors/donors).
Formula of ion of A is A2+. Element A probably belongs to ______ group.
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the valency,
State the nature of compounds formed when group 17 elements combine with (i) metals (ii) non-metals.
An element A has 2 electrons in its fourth shell. State:
is it an oxidising or reducing agent
The electronic configuration of an element is 2, 8, 4. State it:
group and period in the Modern Periodic Table.
The electronic configuration of an element is 2, 8, 4. State it:
name and write its one physical property.
Name the elements in Period 1.
What is the common feature of the electronic configuration of the elements at the end of Period 2 and Period 3?
Select the correct answer from the options given below.
It is a metal in period 2 having electronic configuration 2, 1?
Fill in the blanks from the words A to F given below’.
A: Decreases
B: Increases
C: Remains same
D: Increases by one
E: Electropositive
F: Electronegative
Across a period from left to right in the Modern Periodic Table.
No. of electron shells _________; No. of valence electrons __________: Electronegativity increases Character of elements changes from electropositive to ________.
