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प्रश्न
Write scientific reason.
The third period contains only eight elements even though the electron capacity of the third shell is 18
उत्तर
The third period contains only eight elements even though the electron capacity of the third shell is 18 because there are 10 electrons which are found to have higher energy than the remaining 8 electrons. The universe prefers the path of less energy. The energy of these 10 electrons is equivalent to the energy of the 4th shell electron. That’s why these electrons are not counted in 3rd shell.
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संबंधित प्रश्न
Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
3Li, 14Si, 2He, 11Na, 15P Which of these elements belong to be period 3?
Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
19K, 3Li, 11Na, 4Be Which of these atoms has smallest atomic radius?
An element has its electron configuration as 2,8,2. Now answer the following questions.
i. What is the atomic number of this element?
ii. What is the valency of this element?
iii. What is the group of this element?
iv. To which period does this element belong?
v. With which of the following elements would this element resemble?
`_7N , _4Be , _18Ar , _17CL`
An element has its electron configuration as 2, 8, 2. Now answer the following question.
With which of the following elements would this element resemble?
(Atomic numbers are given in the brackets)
N(7), Be(4), Ar(18), Cl(17)
Which among the following elements would lose an electron easily?
Which among the following is the largest element?
Find the odd one out and give its explanation.
Write the name of noble gas having 2 electrons in its valence shell.
Match the columns.
| Column A | Column B |
| Electronic configuration |
Valency |
| 1) 2, 2 | a) 1 |
| 2) 2, 8, 1 | b) 2 |
| 3) 2, 5 | c) 3 |
| d) 5 |
Match the columns.
| Column A | Column B |
| 1) Alkaline earth metals | a) Group 18 |
| 2) Alkali metals | b) Group 17 |
| 3) Halogen | c) Group 2 |
| 4) Noble gas | d) Group 1 |
| e) Group 14 |
The elements lithium and beryllium are in the same period because their valencies are similar.
Write an Explanation.
Group
In group 2, beryllium and calcium elements, calcium is more electropositive element than beryllium.
Complete the following chart.
| Shell | n | 2n2 | Electron holding capacity |
| K | ______ | 2 × 12 | 2 |
| L | 2 | ______ | 8 |
| ______ | 3 | 2 × 32 | 18 |
| N | 4 | 2 × 42 | ______ |
Find the period in which these elements can be placed.
4Be, 17Cl, 2He, 13Al
Identify periods of elements and blocks of elements from given electronic configuration?
- 2, 8, 2
- 2, 8, 7
- 2, 1
Observe the given chart and answer the questions given below.
| Element | A | B | C | D |
| Electronic configuration | 2, 1 | 2, 8 | 2, 8, 1 | 2, 8, 8 |
- Which elements are in the same row?
- Which elements have the same column?
- Which elements are in the 18th column?
- Which element is more reactive among A and C?
- Which of the following elements A or B will form compounds?
Make a chart which shows the name of the element, valency, atomic number, electronic configuration in the 2nd row of the modern periodic table and arrange these elements in ascending order of atomic mass.
What is the electronic configuration of K19?
