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प्रश्न
Write the electronic configuration of K and Ne.
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उत्तर
| Element | Electronic configuration |
| K | 2,8,8,1 |
| Ne | 2,8 |
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संबंधित प्रश्न
Fill in the blank:
The formulae of chloride of metal M is MCl2. The metal M belongs to ……………. group.
The atomic numbers of three elements A, B and C are 12, 18 and 20 respectively. State, giving reason, which two elements will show similar properties.
Study the following table in which positions of six elements A, B, C, D, E and F are shown as they are in the modern periodic table:
|
Group→
Period↓ |
1
|
2
|
3-12
|
13
|
14
|
15
|
16
|
17
|
18
|
| 2 | A | B | C | ||||||
| 3 | D | E | F |
On the basis of the above table, answer the following questions:-
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of D and E, which is bigger in size and why?
(v) Write the common name for the family to which the elements C and F belong.
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 atomic numbers of two elements 'X' and 'Y' having electronic configuration 2, 8, 2 and 2, 8, 6 respectively.
The following table shows the electronic configuration of the elements W, X, Y, Z:
| Element | w | x | y | z |
| Electronic configurations |
2, 8, 1 | 2, 8, 7 | 2, 5 | 1 |
Answer the following questions based on the table above:
1) What type of Bond is formed between :
a) W and X
b) Y and Z
2) What is the formula of the compound formed between :
a) X and Z
b) W and X
Choose the most appropriate answer of the following:
Which of the following would weigh the least?
(A) 2-gram atoms of Nitrogen.
(B) 1mole of Silver
(C) 22.4 liters of oxygen gas at 1 atmospheric pressure and 273K
(D) 6.02 x 1023 atoms of carbon.
[Atomic masses: Ag=108, N=14, O=16, C=12]
How does the valency of elements vary in going down a group of the periodic table?
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 |
.................... .................... |
.................... .................... |
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?
Why sodium element of group 1 and chlorine element of group 17 both have valency 1?
An element X belong to 4th period and 17th group, state.
no of valence electrons in it
How does the number of:
valency vary on moving from left to right in the second period of the periodic table?
An element barium has atomic number 56. Look up its position in the periodic table and answer the following question.
Is it more or less reactive than calcium?
Complete the following sentences.
The properties of the elements are a periodic function of their …………… (atomic number, mass number, reative atomic mass).
Name the element in period 3 which does not form oxide.
What is the common feature of the electronic configuration of the elements at the end of period 2, and period 3?
F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each.
What will be the valency of an element of atomic number 9 (nine)?
Calculate the valency of element X whose atomic number is 9.
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?
State whether the following statement is true or false
Similar electronic configuration is repeated after intervals of 2, 8, 8, 18 and 32.
'In a group, the atomic radii increase with increasing period number', explain this statement and justify it with reference to group 17.
Select the correct answer
Most reactive character among the elements given below is found in
Atomic number of an element is 16. State
- the period to which it belongs
- the number of valence electrons
- whether it is a metal or non-metal
Choose the most appropriate answer from the following list of oxides which fit the description.
An oxide which dissolves in water forming an acid.
Arrange the following as per instruction given in the bracket.
Li, K, Na, H ( decreasing order of their potential ionisation )
Name and state the following with reference to the elements of the first three periods of the periodic table.
Non-metallic elements present in Period 3 of Groups 15 and 16.
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
Answer the following question:
State the four blocks of the modern periodic table based on the electronic configuration of elements.
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.
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
Name the period which is the shortest period of the periodic table.
Name or state following with reference to the elements of the first three periods of the periodic table.
The number of electron shells in elements of period 1, period 2, and period 3.
Name or state following with reference to the element of the first three periods of the periodic table.
The non-metallic element present in period 3 other than sulphur and chlorine.
Which of the following would weigh the least?
(Atomic masses C = 12, 0 = 16, Na = 23)
