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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
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
The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons in the outermost shell respectively. State the period in which these elements can be placed in the modern periodic table. Write the electronic configuration of the atoms of A and D and the molecular formula of the compound formed when A and D combine.
Which element has a total of three shells, with four electrons in its valence shell?
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
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?
Rewrite the following statement after correction, if necessary:
The metallic character of elements in a period increases gradually on moving from left to right.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
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?
Explain why, the properties of elements are repeated after 2, 8, 18 and 32 elements in the periodic table.
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 ?
The elements A, B, C, D and E have atomic numbers 9, 11, 17, 12 and 13 respectively. The pair of elements which belongs to the same group of the periodic table is:
(a) A and B
(b) B and D
(c) A and C
(d) D and E
The element which has the maximum number of valence electrons is:
(a) Na
(b) P
(c) Si
(d) A
Why sodium element of group 1 and chlorine element of group 17 both have valency 1?
Correct the statements.
Elements in the same periods have equal valency.
What do you understand by orbits?
An element X belong to 4th period and 17th group, state.
Write the formula of the compound formed when it reacts with `(27)/(13) y `
How does the number of:
valence electrons and
An element barium has atomic number 56. Look up its position in the periodic table and answer the following question.
Is it more or less reactive than calcium?
How do the following change on moving from left to right in a period of the periodic table?
Give examples in support of your answer.
atomic structure (electron arrangements) ?
How do the following change on moving from left to right in a period of the periodic table?
Give examples in support of your answer.
Chemical reactivity of elements ?
name the elements in period 1.
What will be the valency of an element of atomic number 9 (nine)?
Fill in the blank
Oxidising property ________from fluroine to iodine because the power to accpet electron decreases.
State the number of elements in period 1, period 2 and period 3 of the periodic table.
How many elements are there in period 2?
In the above table, H does not represent hydrogen.Some elements are given in their own symbol and position in the periodic table while others are shown with a letter. With refrence to the table answer the following questions.
1. Identify the most electronegative element.
2. Identify the most reactive element of Group I.
3. Identify the element from Period 3 with least atomic size.
4. How many valence electrons are present in Q?
5. Which element from group 2 would have the least ionisation energy?
6. Identify the noble gas of the fourth period.
7. In the compound between A and H, what type of bond would be formed and give its molecular formula.
Arrange the following as per instruction given in the bracket.
K, Pb, Ca, Zn (increasing reactivity)
Arrange the following in order of increasing radii:
Mg2+, Mg, Mg+
Arrange the following in order of increasing radii:
N, O, P
Name and state the following with reference to the elements of the first three periods of the periodic table.
Metalloid in Period 3.
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:
Oxide of first group elements.
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.
State the property trends in general of elements on moving down in a group of the periodic table.
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.
Select the correct answer from the options given below.
It is a period having elements from atomic no. 11 to 18.
State the following:
The group which contains highly electropositive metals including sodium.
There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively.
Classify the above elements as metals and non-metals.
