Quantum number

Quantum number is a set of number to express position, orientation and spin of electron within an atom. 

 It express the Size and shape of elliptical path, three dimensional orientation of orbitals and electrons spin. 

 There have four quantum number 

Principle quantum Number

Azimuthal quantum Number

Magnetic Quantum Number

Spin quantum Number

 Principle quantum number

 The number to express size of energy state. it expresses in which energy state electron placed. If electron placed in 3rd energy state, principle quantum number is 3. it is expressed as n. Azimuthal quantum number depends directly on the value of n. Magnetic quantum number depends directly on azimuthal quantum number and indirectly on principle quantum number.

 Azimuthal Quantum number

Azimuthal Quantum Number expresses the sub shell in the energy state. It expresses how number subshell exist within an energy state. It is expresses as l. its value depends on the value of n. its value will be 0 to n-1. 

In 3rd energy state n equal to 3. Hence, azimuthal quantum number will be 0, 1, 2. Hence, s, p, d, orbital is possible in 3rd energy state. 

 Magnetic Quantum Number

  Magnetic Quantum Number expresses orbital number and orientation of orbital. How number of orbital is possible and what types of orbital is possible within an energy state magnetic quantum number indicates it. It's value depends on azimuthal quantum number. For any value of l, it is equal to 2l+1. In 3rd energy state l have value 0, 1, 2. Hence, Magnetic quantum number will be is as bellow, 

For l is 0, magnetic quantum number is 1. Hence a one S orbital is possible in 3rd energy state. 

 For l is 1, magnetic quantum number will be -1, 0, +1 Hence, three orientation of p orbital exist. Px, Py, Pz 

For l equal to 2, Magnetic quantum number will be -2, -1, 0, +1, +2 Hence, 5 orientation of d orbital is possible in 3rd energy state. 

 In 3rd energy state total number of orbital is equal to 9. Spin quantum Number: The spin of electron will be + half and - Half.