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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
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?
List any two properties of the elements belonging to the first group of the modern periodic table.
Based on the group valency of elements state the formula lot the following giving justification for each :-
(i) Oxides of 1st group elements,
(ii) Halides of the elements of group 13, and
(iii) Compounds formed when an element of group 2 combines with, an element of group 16.
How do the valency and the atomic size of the elements vary while going from left to right along a period in the modern periodic table?
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]
Fill in the blank in the following statement:
The tendency to gain an electron ............... on moving down in a group of the periodic table.
An element X belongs to group 2 and another element Y belongs to group 15 of the periodic table:
(a) What is the number of valence electron in X?
(b) What is the valency of X?
(c) What is the number of valence electrons in Y?
(d) What is the valency of Y?
Explain how you have arrived at your answers.
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?
How does the atomic size vary on going down from top to bottom in a group of the periodic table? Why does it vary this way?
How does the tendency to gain electrons change as we go down in group 17 of the periodic table? Why does it change this way?
In which part of a group would you separately expect the elements to have the largest atomic size?
The electronic configuration of the atom of an element X is 2, 8, 4. In modern periodic table, the element X is places in :
(a) 2nd group
(b) 4th group
(c) 14th group
(d) 8th group
Which of the following element would lose an electron easily?
(a) Mg
(b) Na
(c) K
(d) Ca
Where would you locate the element with electronic configuration 2, 8 in the modern periodic table?
What do you understand by periodicity?
What is its atomic number?
An element has 2 electrons in its N shell.
State the name assigned to this group.
An element X belong to 4th period and 17th group, state.
name of the element.
Complete the following sentences.
The properties of the elements are a periodic function of their …………… (atomic number, mass number, reative atomic mass).
Name the non-metals present in period 2 and metals in period 3.
State the number of elements in periods 1, Periods 2, and Period 3 of the periodic table. Name them.
What is the common feature of the electronic configuration of the elements at the end of period 2, and period 3?
What will be the valency of an element of atomic number 9 (nine)?
How many groups and periods are there in the modern periodic table?
Fill in the blank
There are ______ groups and ______ periods in the modern form of periodic table.
The elements of one short period of the periodic table are given below in order from left to right:
Li Be B C O F Ne
(a) To which period do these elements belong?
(b) One element of this period is missing. Which is the missing element and where should it be placed?
(c) Place the three elements, fluorine, beryllium and nitrogen, in the order of increasing electro negativity.
(d) Which one of the above elements belongs to the halogen series?
Consider the section of the periodic table given below :
| Group numbers |
IA | IIA | IIIA | IVA | VA | VIA | VIIA | O |
| 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 | |
| Li | D | O | J | Ne | ||||
| A | Mg | E | Si | H | K | |||
| B | C | F | G | L |
With reference to the table, answer the following :
(i) Which is the most electro negative ?
(ii) How many valence electrons are present in G ?
(iii) Write the formula of the compound between B and H ?
(iv) In the compound between F and J, what type of bond will be formed ?
(v) Draw the electron dot structure for the compound formed between C and K.
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 as per instruction given in the bracket.
Cs, Na, Li, K, Rb (increasing metallic character)
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 |
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|
A |
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|
E |
Which type of ion will be formed by elements A, B, and C.
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 |
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A |
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E |
Which is larger in size (i) D or E (ii) B or C
Write the electronic configuration of element 17T35.
- What is the group number of T?
- What is the period number of T?
- How many valence electrons are there in an atom of T?
- What is the valency of T?
- Is it a metal or non-metal?
- State number of protons and neutrons in T.
State the nature of compounds formed when group 17 elements combine with (i) metals (ii) non-metals.
(a) Fill in the blanks and rewrite the completed statements:
(i) ________ group in the periodic table contains elements that are all gases at room temperature.
(ii) Very fine particles mainly scatter ______ light.
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 non-metallic element present in period 3 other than sulphur and chlorine.
