Principle Quantum Number

The principle quantum number is one of the four quantum numbers that describe the properties of an electron in an atom. It is denoted by the letter 'n'.

Description

The principle quantum number describes the size or energy level of an orbital. It determines the distance of the electron from the nucleus and the amount of energy required to remove the electron from its orbital. It can have whole number values of 1, 2, 3, and so on.

Features

1. Energy level: The energy of an electron is directly proportional to the principle quantum number. As the value of n increases, the energy level of the electron also increases.

2. Size of the orbital: The size of the orbital also increases with the increase in the value of n. The size of the orbital describes the distance of the electron from the nucleus.

3. Number of orbitals: The number of orbitals in an energy level is equal to the square of the principle quantum number. For example, if the value of n is 3, then the number of orbitals in the third energy level is 9.

4. Electrons in an energy level: The maximum number of electrons that can be accommodated in an energy level is given by the formula 2n². For example, if the value of n is 3, then the maximum number of electrons that can be accommodated in the third energy level is 18.

Conclusion

Thus, the principle quantum number describes the size of the orbital and the energy level of the electron. It is an important quantum number that helps in understanding the electronic configuration of an atom.

The ans is (a)Size of the orbitalBcoz... The size of the orbital depends upon the value of principal quantum number(n). Greater the value of n, larger is the size of the orbital.  (b)Shape of the orbital is explained by Azimithal quantum no.(l) The value varies from 0 to (n-1)(c)Spin of the orbital is given by Spin quantum no.(s) The value of s is +1/2 or -1/2 (d)Orientation of an orbital is given by Magnetic quantum no.(m) The value of m is from +ĺ to -ĺ... Hope u get it....😄😄😄