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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
The atomic masses of three elements A, B and C having similar chemical properties are 7, 23 and 39, respectively.
- Calculate the average atomic mass of elements A and C.
- Compare the average atomic mass with atomic mass of B.
- What could the elements A, B and C be?
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.
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
An element 'X' has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'.
Name any two elements of group one and write their electronic configurations. What similarity do you observe in their electronic configurations? Write the formula of oxide of any of the aforesaid elements.
List any two properties of the elements belonging to the first group of the modern periodic table.
Write the number of vertical columns in the modern periodic table. What are these columns called?
Define the term : Atomic size
Use the letters only written in the Periodic Table given below to answer the questions that Follow:
- State the number of valence electrons in atom J.
- Which element shown forms ions with a single negative charge?
- Which metallic element is more reactive than R?
- Which element has its electrons arranged in four shells?
Name the element which is in first group and third period.
Rewrite the following statement after correction, if necessary:
Elements in the same period have equal valency
Fill in the blank in the following statement:
The tendency to gain an electron ............... on moving down in a group of the periodic table.
Periodicity is observed due to the similar ______.
Correct the statements.
Elements in the same periods have equal valency.
Complete the following sentences.
The properties of the elements are a periodic function of their …………… (atomic number, mass number, reative atomic mass).
name the elements in period 1.
Write two reasons responsible for the late discovery of noble gases?
An element 'M' has atomic number 12.
(a) Write its electronic configuration.
(b) State the group to which 'M' belongs.
(c) Is 'M' a metal or a non-metal.
(d) Write the formula of its chloride.
How do you calculate the possible valency of an element from the electronic configuration of its atoms?
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?
Arrange the following according to the instruction given in the bracket:
K, Pb, Ca, Zn (in the increasing order of the reactivity).
What is meant by periodicity of elements?
Select the correct answer
Number of shells in potassium are
State the number of elements in period 1, period 2 and period 3 of the periodic table.
Parts (i) to (v) refer to changes in the properties of elements on moving from left to right across a period of the periodic table. For each property, choose the letter corresponding to the correct answer from the choices (a), (b), (c) and (d).
(i) The non metallic character of the elements:
(a) Decreases
(b) Increases
(c) Remains the same
(d) Depends on the period
(ii) The electro negativity
(a) Depends on the number of valence electrons
(b) Remains the same
(c) Decreases
(d) Increases
(iii) The ionization potential
(a) Goes up and down
(b) Decreases
(c) Increases
(d) Remains the same
(iv) The atomic size
(a) Decreases
(b) Increases
(c) Remains the same
(d) Sometimes increases and sometimes decreases
(v) The electron affinity of the elements in groups 1 to 7:
(a) Goes up and down
(b) Decreases and then increases
(c) Increases
(d) decreases
Choose the correct answer from the choice given:
An element A belonging to Period 3 and Group II will have
Arrange the following as per instruction given in the bracket.
Cl, F, Br, I (increasing electron affinity)
Arrange the following as per instruction given in the bracket.
Cs, Na, Li, K, Rb (decreasing electronegativity)
Arrange the following as per instruction given in the bracket.
Li, K, Na, H ( decreasing order of their potential ionisation )
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).
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?
Element P has atomic number 19. To which group and period, does P belong? Is it a metal or a non-metal? Why?
Moving down in the second group, number of valence electrons ______.
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
The similarities in the properties of a group of elements are because they have the same ______.
Select the correct answer from the options given below.
It is a metal in period 2 having electronic configuration 2, 1?
