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प्रश्न
Elements in the same group show the same valency. Give scientific reason.
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उत्तर
(a) The number of valence electrons in the outermost shell of an atom of an element is equal to the valency of an element.
(b) The number of valence electrons for all the elements in a group is the same. Therefore, the elements in the same group have the same valency.
(c) For example, the elements of Group I such as sodium (Na) and potassium (K) contain only one valence electron, and so, the valency of elements of Group I is one. Similarly, for Group II, the valency is two.
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संबंधित प्रश्न
Na, Mg and Al are the elements of the same period of Modern Periodic Table having, one, two and three valence electrons respectively. Which of these elements (i) has the largest atomic radius, (ii) is least reactive? Justify your answer stating reason for each case.
Define the term : Atomic size
Write any one difference in the electronic configurations of group-1 and group-2 elements ?
Use the letters only written in the Periodic Table given below to answer the questions that Follow :
1) State the number of valence electrons in atom J.
2) Which element shown forms ions with a single negative charge?
3)Which metallic element is more reactive than R?
4) Which element has its electrons arranged in four shells?
In the following set of elements, one element does not belong to the set. Select this element and state why it does not belong:
Oxygen, Nitrogen, Carbon, Chlorine, Fluorine
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?
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
Five elements A, B, C, D and E have atomic numbers of 2, 3, 7, 10 and 18 respectively. The elements which belong to the same period of the periodic table are:
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) B, D, E
Given alongside is a part of the periodic table. As we move vertically downward from Li to Fr:
| Li | Be |
| Na | |
| K | |
| Rb | |
| Cs | |
| Fr | Ra |
What happens to their metallic character?
Which of the following element would lose an electron easily?
(a) Mg
(b) Na
(c) K
(d) Ca
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
Which one of the following does not increase while moving down the group of the periodic table?
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 which has the electronic configuration 2, 8, 3?
Name the element in period 3 which does not form oxide.
State the number of elements in periods 1, Periods 2, and Period 3 of the periodic table. Name them.
Calculate the valency of element X whose atomic number is 9.
On the basis of electronic configuration, how will you identify the first and the last element of a period?
K, Pb, Ca, Zn (In the increasing order of the reactivity)
Fill in the blank
Most electropositive elements belong to ______ group.
State whether the following statement is true or false
On moving horizontally across a period, number of valence electrons increases from one to eight.
Explain
Size of atom changes when it loses or gain electron
Select the correct answer
Number of shells in potassium are
What is the common feature of electronic configurations of the elements at the end of period 2 and period 3?
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 correct answer from the choice given:
An element A belonging to Period 3 and Group II will have
Arrange the following in order of increasing radii:
N, O, P
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 |
To which period do these elements belong?
Formula of ion of A is A2+. Element A probably belongs to ______ group.
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.
Name and state the following with reference to the elements of the first three periods of the periodic table.
Metalloid in Period 3.
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:
its valency
(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.
Fill in the blank and rewrite the completed statement:
________ group in the periodic table contains elements that are all gases at room temperature.
The position of certain elements in the Modern Periodic Table is shown below:
| Group → Period ↓ |
1 | 2 | 3 to 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 1 | G | H | |||||||
| 2 | A | I | B | C | |||||
| 3 | D | E | F |
Using the above table answer the following questions giving reasons in each case:
- Which element will form only covalent compounds?
- Which element is a non-metal with valency 2?
- Which element is a metal with valency 2?
- Out of H, C, and F which has the largest atomic size?
- To which family does H, C, and F belong?
What is the common feature of the electronic configuration of the elements at the end of Period 2 and Period 3?
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.
A non-metal in period 2 which is tetravalent.
