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प्रश्न
Given below are some elements of the modern periodic table. Atomic number of the element is given in parentheses.
A(4), B(9), C(14), D(19), E(20)
(a) Select the element that has one electron in the outermost shell. Also, write the electronic configuration of this element.
(b) Which two elements amongst these belong to the same group? Give reasons for your answer.
(c) Which two elements amongst these belong to the same period? Which one of the two has bigger atomic radius?
Given below are some elements of the modern periodic table: (3)
4Be, 9Fe, 14Si, 19K, 20Ca
(i) Select the element that has one electron in the outermost shell and write its electronic configuration.
(ii) Select two elements that belong to the same group. Give reason for your answer.
(iii) Select two elements that belong to the same period. Which one of the two has bigger atomic size?
उत्तर
(a) Element D (19) has one electron in its outermost shell. Its electronic configuration is 2, 8, 8, 1.
(b) Elements A (4) and E (20) have two electrons in their outermost shells.
Electronic configuration of A: 2, 2
Electronic configuration of E: 2, 8, 8, 2
Since they both have a valency of two, they belong to group 2 of the periodic table.
(c) Elements A (4) and B (9) belong to the second period, and elements D (19) and E (20) belong to the fourth period of the periodic table.
Since the effective nuclear charge which pulls the outermost electron closer to the nucleus increases from left to right in a period, the atomic radii of the elements decreases. A (4) has a bigger atomic radius than B (9) and D (19) has a bigger atomic radius than E (20).
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संबंधित प्रश्न
Given alongside is a part of the periodic table. As we move vertically downward from Li to Fr:
| Li | Be |
| Na | |
| K | |
| Rb | |
| Cs | |
| Fr | Ra |
What happens to their metallic character?
Correct the statements.
Elements in the same periods have equal valency.
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?
Which element has:
twice as many electrons in its second shell as in its first shell?
Consider the section of the periodic table given below :
| Group numbers |
IA | IIA | IIIA | IVA | VA | VIA | VIIA | O |
| 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 | |
| Li | D | O | J | Ne | ||||
| A | Mg | E | Si | H | K | |||
| B | C | F | G | L |
With reference to the table, answer the following :
(i) Which is the most electro negative ?
(ii) How many valence electrons are present in G ?
(iii) Write the formula of the compound between B and H ?
(iv) In the compound between F and J, what type of bond will be formed ?
(v) Draw the electron dot structure for the compound formed between C and K.
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.
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.
An amphoteric oxide.
The elements of one short period of the periodic table are given below in order from left to right:
| Li | Be | B | C | O | F | Ne |
Place the three elements fluorine, beryllium and nitrogen in the order of increasing electronegativity.
State the nature of compounds formed when group 17 elements combine with (i) metals (ii) non-metals.
