Quantum number is very important topics of discussion in chemistry. To explain the position and energy level of electron in an atom quantum number plays an important role in chemistry. Due to having the limitation of Bohrs electronic shell it is necessary to introduce different quantum number.
What is quantum number? Quantum number is the numerical value that usually used for determining the energy, position, orientation as well as Goody's behavior of electron In an atom. It gives the description of electrons.
Types of quantum number
There have four kinds of quantum number. These are principal quantum number, azimuthal quantum number, magnetic quantum number and spin quantum number.
Why four kinds of quantum number is necessary? Principle quantum which is called Bohr's electronic shell can explain only the spectrum of hydrogen atom. But it faild to explain the spectrun of other atoms. Not only that, but also Zeeman effect and Stark effect is unexplained.To overcome the limitation of principal quantum number another three quantum number is introduced these are azimuthat quantum number, magnetic quantum number and spin quantum number.
Different kinds of quantum number is explained bellow
Principal quantum number
Principal quantum number is also called Bohrs electronic shell. The principal electronic shell indicates the shell surrounding the nucleus where electron belongs to. It is the energy level of an electron. Principal quantum number is denoted by symbol n. Principal quantum number expresses the average size of electron clouds and dostance of an electron and the nucleus
Principle quantum number is indicated for expressing the number of shell In which the electron is presents. If the principle quantum number of an electron is 1, that indicates the electron revolving surrounding the nucleus is present In first shell. It as provide information about distance of electron from nucleus as well as the maximum number of electron containing capability by a shell. According to Hoie Bury scheme, a shell can contain the number of electron equal to the twice of square of principle quantum number.
Azimuthal quantum number
Azimuthal quantum number is introduced to define the spatial distribution of electron cloud and the angular momentum of the electron. The shape of the electron cloud is possible to describe by azimuthal quantum number. One can calculate azimuthal quantum number if he know the principal quantum number. If the principal quantum number is n, then the azimuthal quantum number will be zero to n-1. If principal quantum number is 2 then azimuthal quantum number will be zero and one.
Magnetic quantum number
Magnetic quantum number is these kinds of quantum number that can explain the splitting of spectral line with the effects of magnetic field. The splitting of spectral line with effect of magnetic field is also designated as Zeeman effect. Magnetic quantum number is also called orientation quantum number. The magnetic quantum number gives the orientation of the distribution of electron clouds in space. Hence, magnetic quantum number is called orientation quantum number. For azimuthal quantum number l, the value of magnetic quantum number will be 2l+1.
Spin quantum number
Spin quantum number is that kinds of quantum number that explain the spin of electron in its own axis. Spin of electron is two kinds. One is clockwise and another is anticlokwise.
Above three quantum number is found in the solution of Schrödinger wave equation for hydrogen. But Schrödinger wave equation and its solution do not give us any idea of spin quantum number. This quantum number is found from the conception of electrons revolving surrounding the nucleus . When electron revolve surrounding the nucleus it shows two types of motion. One is revolving of electron by an elliptical path surrounding the nucleus according to Rutherford's view and another motion is a spin movement along with its own axis. <
