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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
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 'M' with electronic configuration (2, 8, 2) combines separately with (NO3)–, (SO4)2– and (PO4)3– radicals. Write the formula of the three compounds so formed. To which group and period of the Modern Periodic Table does the element 'M' belong? Will 'M' form covalent or ionic compounds? Give reason to justify your answer.
Two elements ‘A’ and ‘B’ belong to the 3rd period of Modern periodic table and are in group 2 and 13, respectively. Compare their following characteristics in tabular form:-
(a) Number of electrons in their atoms
(b) Size of their atoms
(c) Their tendencies to lose electrons
(d) The formula of their oxides
(e) Their metallic character
(f) The formula of their chlorides
Define the term : Valency
Which element has twice as many electrons in its second shell as in its first shell?
Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)
Differentiate between Normal elements and Transition elements.
How does the valency of elements change of moving from left to right in the third period of the periodic table?
Fill in the blank in the following statement:
On moving form right to left in the second period, the number of valency electrons ...............
Fill in the blank in the following statement:
On going down in a group in the periodic table, the metallic character of elements ...............
How does the electropositive character of elements change on going down in a group of the periodic table?
Why do elements in the same group show similar properties but the elements in different groups show different properties?
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 |
.................... .................... |
.................... .................... |
In which part of a group would you separately expect the elements to have the largest atomic size?
In terms of electronic configurations, explain the variation in the size of the atoms of the elements belonging to the same period and same 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?
An element X belong to 4th period and 17th group, state.
no of valence electrons in it
An element X belong to 4th period and 17th group, state.
name of the element.
An element X belong to 4th period and 17th group, state.
name the family to which it belong.
Chorine in the periodic table is surrounded by the elements with atomic number 9, 16, 18 and 35.
Which of these have physical and chemical properties resembling chlorine.
Chorine in the periodic table is surrounded by the elements with atomic number 9, 16, 18 and 35.
Which is more electronegative than chlorine?
Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element. 
Which is an inert gas?
What is modern periodic law?
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 ______
What is meant by a group in the periodic table?
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 the instruction given in the bracket
He,Ar,Ne (Increasing order of the number of electron shells)
Arrange the following as per instruction given in the bracket.
K, Pb, Ca, Zn (increasing reactivity)
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.
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.
Moving left to right in the second period, the number of valence electrons _____.
An element A has 2 electrons in its fourth shell. State:
position in the periodic table
Based on the group valency of element write the molecular formula of the following compound giving justification:
Compound formed when an element A of group 2 combines with an element B of group seventeen.
Write the electronic configuration of two elements A and B whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element A reacts with element B. State whether this compound is acidic, basic or neutral. Give a reason to justify your answer.
Supply the missing word from those in bracket:
If an element has one electron in its outermost energy level [shell] then it is likely to be _______.
What is meant by a Group in the Periodic Table?
Select the correct answer from the options given below.
Is the group number of the element whose atomic number is 4.
