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प्रश्न
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?
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उत्तर
- Li > Be > B > C > N > O
- 2nd period
- Yes, this elemental arrangement resembles the era of the contemporary periodic table mentioned above. The positive charge on the nucleus grows one unit at a time as we move from left to right over a period of time, but when electrons are added to the same orbit, the pull away from the nucleus increases, reducing the size of the atom.
- Li is the biggest atom oxygen is the smallest atom
- While going from left to right within a period atomic radius decreases due to an increase in effective nuclear charge.
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संबंधित प्रश्न
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.
How do the atomic size and metallic character of elements vary as we move?
- down a group and
- from left to right in a period
From the following elements :
4Be; 9F; 19K; 20Ca
(i) Select the element having one electron is the outermost shell.
(ii) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2, 8, 7).
Na, Mg and Al are the elements of the same period of Modern Periodic Table having, one, two and three valence electrons respectively. Which of these elements (i) has the largest atomic radius, (ii) is least reactive? Justify your answer stating reason for each case.
Write the atomic numbers of two elements 'X' and 'Y' having electronic configuration 2, 8, 2 and 2, 8, 6 respectively.
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?
Name the element that has two shells, both of which are completely filled with electrons.
Use the letters only written in the Periodic Table given below to answer the questions that Follow:
- State the number of valence electrons in atom J.
- Which element shown forms ions with a single negative charge?
- Which metallic element is more reactive than R?
- Which element has its electrons arranged in four shells?
The following table shows the electronic configuration of the elements W, X, Y, Z:
| Element | w | x | y | z |
| Electronic configurations |
2, 8, 1 | 2, 8, 7 | 2, 5 | 1 |
Answer the following questions based on the table above:
1) What type of Bond is formed between :
a) W and X
b) Y and Z
2) What is the formula of the compound formed between :
a) X and Z
b) W and X
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:
The tendency to gain an electron ............... on moving down in a group of the periodic table.
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 correct increasing order of the atomic radii of the elements oxygen, fluorine and nitrogen is:
(a) O, F, N
(b) N, F, O
(c) O, N, F
(d) F, O, N
Why sodium element of group 1 and chlorine element of group 17 both have valency 1?
Periodicity is observed due to the similar ______.
What do you understand by orbits?
Name two elements you would expect to show chemical reactions similar to calcium. What is the basis of your choice?
State the valency of the elements of periods 3 and write the formula of their oxides.
State the trends in physical properties on moving down the group. Give an example to illustrate.
State the number of elements in periods 1, Periods 2, and Period 3 of the periodic table. Name them.
In the following table, the positions of six elements A, B, C, D, E and F are given as they are in the Modern Periodic Table :
 |
1 | 2 | 3-12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 2 | A | B | C | D | |||||
| 3 | E | F |
On the basis of the above table, answer the following questions :
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of B and C, whose atomic radius is bigger and why ?
(v) Write the common name for the family to which the elements D and F belong.
Write two reasons responsible for the late discovery of noble gases?
Arrange the following according to the instruction given in the bracket:
K, Pb, Ca, Zn (in the increasing order of the reactivity).
What is modern periodic law?
Fill in the blank
Oxidising property ________from fluroine to iodine because the power to accpet electron decreases.
Consider the section of the periodic table given below:
| Group numbers | IA | IIA | IIIA | IVA | VA | VIA | VIIA | 0 |
| 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 | |
| Li | D | O | J | Ne | ||||
| A | Mg | E | Si | H | K | |||
| B | C | F | G | L |
Note: In this table B does not represent boron
C does not represent carbon
F does not represent fluorine
H does not represent hydrogen
K does not represent potassium
You must see the position of the element in the periodic table.
Some elements are given in their own symbol and position in the periodic table, while others are shown with a letter. With reference to the table answer the following:
- Which is the most electronegative?
- How many valence electrons are present in G?
- Write the formula of the compound between B and H.
- In the compound between F and J, what type of bond will be formed?
- Draw the electron dot structure for the compound formed between C and K.
Choose the correct answer from the choice given:
An element A belonging to Period 3 and Group II will have
Arrange the following as per instruction given in the bracket.
Cl, F, Br, I (increasing electron affinity)
Arrange the following as per instruction given in the bracket.
Cs, Na, Li, K, Rb (decreasing electronegativity)
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the name of the element.
Going across a period left to right, atomic size _____.
An element A has 2 electrons in its fourth shell. State:
is it a metal or non-metal
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 covalent compound formed between an element in period 1 and a halogen.
Select the correct answer from the options given below.
It is a metal in period 2 having electronic configuration 2, 1?
