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प्रश्न
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उत्तर
Atomic size increases down the group
- The atomic numbers of the elements increase as we go down the group. Thus, the elements placed lower have more electrons.
- To accommodate these electrons new shells are added to the atom.
- These new shells take the outermost electrons farther from the nucleus causing atomic size (radius) to increase as we go down the group.
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संबंधित प्रश्न
Elements in the same group show the same valency. Give scientific reason.
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 elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively of the modern periodic table. Answer the following questions, giving justification in each case:-
(i) Write the group to which these elements belong.
(ii) Name the least reactive element.
(iii) Name the element having largest atomic radius.
Calcium is an element with atomic number 20. Stating reason, answer each of the following questions:-
(i) Is calcium a metal or a non-metal?
(ii) Will its atomic radius be larger or smaller than that of potassium with atomic number 19?
(iii) Write the formula of its oxide.
Write the number of periods the Modern Periodic Table has. State the changes in valency and metallic character of elements as we move from left to right in a period. Also state the changes, if any, in the valency and atomic size of elements as we move down a group.
Write the number of vertical columns in the modern periodic table. What are these columns called?
Consider two elements 'X' (Atomic number 17) and 'Y' (Atomic number 20)
(i) Write the positions of these elements in the modern periodic table giving justification.
(ii) Write the formula of the compound formed by the combination of 'X' and 'Y'.
(iii) Draw the electron-dot structure of the compound formed and state the nature of the bond formed between the two elements ?
How does the number of valence electrons vary on moving from left or right in the first period of the periodic table?
Name the element which is in seventeenth group and second period.
How do atomic structures (electron arrangements) change in a period with increase in atomic numbers from left to right?
How does the size of atoms (atomic size) generally vary in going from left to right in a period of the periodic table? Why does it vary this way?
How does the tendency to lose electrons change as we go down in group 1 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.
The atomic number of an element is 20. In modern periodic table, this element is placed:
(a) 2nd period
(b) 4th period
(c) 3rd period
(d) 1st period
Five elements A, B, C, D and E have atomic numbers of 2, 3, 7, 10 and 18 respectively. The elements which belong to the same period of the periodic table are:
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) B, D, E
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
Where would you locate the element with electronic configuration 2, 8 in the modern periodic table?
What do you understand by orbits?
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 ?
First ionization enthalpy of two elements X and Y are 500 KJ mol-1 and 375 KJ mol-1 respectively. Comment about their relative position in a group as well as in a period.
Calculate the valency of element X whose atomic number is 9.
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).
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. 
The ion of which element will migrate towards the cathode during electrolysis?
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?
Fill in the blank
Oxidising property ________from fluroine to iodine because the power to accpet electron decreases.
Explain, the statement 'In each period, the atomic radii gradually decrease with increase in atomic number'. Give one example to justify your answer.
Explain
Size of atom changes when it loses or gain electron
What is meant by a group in the periodic table?
How many elements are there in period 2?
The following questions refer to the Periodic Table.
What is the common feature of the electronic configurations of the elements in group 7?
An element Z has atomic number 16. Answer the following
(a) State the period and group to which Z belongs
(b) Is Z a metal or a non-metal?
(c) State the formula between Z and hydrogen.
(d) what kind of a compund is this?
Choose the most appropriate answer from the following list of oxides which fit the description.
A basic 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)
With reference to the variation of properties in the Periodic table, which of the following is generally true?
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the name of the element.
Name or state following with reference to the elements of the first three periods of the periodic table.
A metalloid in period 2 and in period 3.
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.
