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प्रश्न
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उत्तर
Atomic size increases down the group
- The atomic numbers of the elements increase as we go down the group. Thus, the elements placed lower have more electrons.
- To accommodate these electrons new shells are added to the atom.
- These new shells take the outermost electrons farther from the nucleus causing atomic size (radius) to increase as we go down the group.
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संबंधित प्रश्न
Write the electronic configuration of K and Ne.
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.
The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis.
| Period No. | ||
| 2 | Li(3) | Be(4) |
| 3 | Na(11) | Mg(12) |
| 4 | K(19) | Ca(20) |
| 5 | Rb(37) | Sr(38) |
(i) Write the electronic configuration of Ca.
(ii) Predict the number of valence electrons in Rb.
(iii) What is the number of shells in Sr?
(iv) Predict whether K is a metal or a non – metal.
(v) Which one of these elements has the largest atom in size?
(vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms.
Calcium is an element with atomic number 20. Stating reason, answer each of the following questions:-
(i) Is calcium a metal or a non-metal?
(ii) Will its atomic radius be larger or smaller than that of potassium with atomic number 19?
(iii) Write the formula of its oxide.
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?
- down a group and
- from left to right in a period
From the following elements :
4Be; 9F; 19K; 20Ca
(i) Select the element having one electron is the outermost shell.
(ii) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2, 8, 7).
Write the number of vertical columns in the modern periodic table. What are these columns called?
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 ?
Match the atomic number 2, 4, 8, 15 and 19 with each of the following:
- A solid non-metal belonging to the third period.
- A metal of valency 1.
- A gaseous element with valency 2.
- An element belonging to Group 2.
- A rare gas.
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]
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]
The atomic radii of three elements X, Y and Z of a period of the periodic table are 186 pm; 104 pm and 143 pm respectively. Giving a reason, arrange these elements in the increasing order of atomic numbers in the period.
How does Nature of oxides of elements change on going from left to right in a period of the periodic table?
Give examples in support of your answer.
How does the size of atoms (atomic size) generally vary in going from left to right in a period of the periodic table? Why does it vary this way?
Where would you locate the element with electronic configuration 2, 8 in the modern periodic table?
The atomic numbers of the elements Na, Mg, K and Ca are 11, 12, 19 and 20 respectively. The element having the largest atomic radius is:
(a) Mg
(b) Na
(c) K
(d) Ca
The element which has the maximum number of valence electrons is:
(a) Na
(b) P
(c) Si
(d) A
On moving from left to right in a period of the periodic table, the atomic number of elements increases. What happens to the size of atoms of elements on moving from left to right in a period?
(a) increases
(b) decreases
(c) remain the same
(d) first increases then decreases
An element X belong to 4th period and 17th group, state.
no of valence electrons in it
An element X belong to 3rd periods and group II of the periodic table state:
name of the element,
Which element has:
twice as many electrons in its second shell as in its first shell?
Name the non-metals present in period 2 and metals in period 3.
Calculate the valency of element X whose atomic number is 9.
Copy and complete the following sentence choosing the correct word or words from those given below, at the end of the sentence:
The similarities in the properties of elements belonging to a group are because they have the same ______
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
Choose the most appropriate answer from the following list of oxides which fit the description.
An amphoteric oxide: Al2O3 (shows both acidic and basic properties)
Arrange the following in order of increasing radii:
N, O, P
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 metals, non-metals, and noble gas in this table.
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 |
Which is larger in size (i) D or E (ii) B or C
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the name of the element.
Moving down in the second group, number of valence electrons ______.
The electronic configuration of an element is 2, 8, 4. State it:
group and period in the Modern Periodic Table.
The similarities in the properties of a group of elements are because they have the same ______.
Name or state following with reference to the element of the first three periods of the periodic table.
The valency of elements in group 1 [I–A].
Name or state following with reference to the element of the first three periods of the periodic table.
The formula of the hydroxide of the element having electronic configuration 2, 8, 2.
Give a reason for the following:
A transition from metallic to non-metallic elements is seen on moving from left to right in a period of the periodic table.
