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प्रश्न
Write a note on ‘Principal Quantum number.
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उत्तर
Principal quantum number (n):
- Principal quantum number indicates the principal shell or main energy level to which the electron belongs.
- It is denoted by ‘n’ and is a positive integer with values 1, 2, 3, 4, 5, 6, ….
- A set of atomic orbitals with a given value of ‘n’ constitutes a single shell. These shells are also represented by the letters K, L, M, N, etc.
- With an increase of ‘n’, the number of allowed orbitals in that shell increases and is given by n2.
- The allowed orbitals in the first four shells are given below:
Principal quantum number (n) Shell symbol Allowed number of orbitals (n2) Size of shell 1 K 1 ↓ increases 2 L 4 3 M 9 4 N 16 - As the value of ‘n’ increases, the distance of the shell from the nucleus increases, and the size of the shell increases. Its energy also goes on increasing.
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संबंधित प्रश्न
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Which of the following sets of quantum numbers are correct?
| `n` | `l` | `m_l` | |
| (i) | 1 | 1 | +2 |
| (ii) | 2 | 1 | +1 |
| (iii) | 3 | 2 | –2 |
| (iv) | 3 | 4 | –2 |
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3dxy, 4dxy 3dz2, 3dyz, 4dyz, 4dz2
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Based upon the above information, arrange the following orbitals in the increasing order of energy.
5f, 6d, 7s, 7p
Match the quantum numbers with the information provided by these.
| Quantum number | Information provided |
| (i) Principal quantum number | (a) orientation of the orbital |
| (ii) Azimuthal quantum number | (b) energy and size of orbital |
| (iii) Magnetic quantum number | (c) spin of electron |
| (iv) Spin quantum number | (d) shape of the orbital |
Which of the following is the correct plot for the probability density ψ2 (r) as a function of distance 'r' of the electron from the nucleus for 2s orbitals?
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