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प्रश्न
The elements 4Be, 12Mg and 20Ca, each having two valence electrons in their valence shells, are in periods 2, 3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case:
(a) In which group should they be?
(b) Which one of them is least reactive?
(c) Which one of them has the largest atomic size?
उत्तर
(a) All three elements have valency 2. Thus, they should be present in group 2 of the periodic table.
(b) On going down a group in the periodic table, the reactivity of an element increases because of decrease in the effective nuclear charge and increase in the atomic size; this makes the removal of valence electrons easy. Thus, among the given elements, 4Be is the least reactive element.
(c) On going down a group in the periodic table, the atomic size of elements increases because of the addition of new shells. Thus, among the given elements, 20Ca has the largest atomic size.
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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
Write the number of horizontal rows in the modern periodic table. What are these rows called?
Correct the statements.
Elements in the same periods have equal valency.
Fill in the blank:
on moving from right to left in the second period, the number of valence electrons……….
F, Cl and Br are the elements each having seven valence electrons. Which of these (i) has the largest atomic radius, (ii) is most reactive? Justify your answer stating reason for each.
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.
Choose the most appropriate answer from the following list of oxides which fit the description.
An amphoteric oxide.
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)
Element P has atomic number 19. To which group and period, does P belong? Is it a metal or a non-metal? Why?
