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प्रश्न
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?
उत्तर
Variation in valency
On moving from left to right in the periodic table, valency increases up to 4 and then decreases.
- The electrons present in the last shell determine the valency of a particular element.
- If the number of valence electrons is less than or equal to 4, valency = number of valence electrons
- If the number of valence electrons is more than 4, valency = 8 - number of valence electrons
Variation in atomic size:-
Atomic size decreases along a period. This is because on moving across a period, the number of valence shells remains the same and the electrons increase by one unit. As a result, the nuclear charge increases and thus, the atomic radius decreases.
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संबंधित प्रश्न
Write the number of horizontal rows in the modern periodic table. What are these rows called?
Differentiate between Normal elements and Transition elements.
Arrange the following elements in the increasing order of their metallic character:
Mg, Ca, K, Ga
Rewrite the following statement after correction, if necessary:
Elements in the same period have equal valency
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
Which of the following is the valence shell for the elements of second period of the modern periodic table?
(a) M shell
(b) K shell
(c) L shell
(d) N shell
Four elements P, Q, R and S belong to the third period of the Modern Periodic Table and have respectively 1, 3, 5 and 7 electrons in their outermost shells. Write the electronic configurations of Q and R and determine their valences. Write the molecular formula of the compound formed when P and S combine.
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.
Name or state following with reference to the elements of the first three periods of the periodic table.
The number of electron shells in elements of period 1, period 2, and period 3.
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.
