Before we know how to write the

When the Schrodinger wave equation is solved for a system, the solutions obtained from it gives us the possible energy levels that the electrons can occupy and the corresponding wave function(s) of the electrons associated with each energy level. The solution to the Schrodinger wave equation for a system gives us the quantized energy states which an electron can occupy and is characterized by a set of three quantum numbers:

Every shell has a fixed number of atomic orbitals and as the value of n increases, the number of allowed atomic orbitals also increase accordingly. Every shell is designated a value which is basically the principal quantum number. So, for the 1

n = 1 2 3 4…

Shell= K L M N…

So, we can say that, every subshell is assigned an Azimuthal quantum number, l and for every subshell we have a corresponding symbol in order to designate the subshell.

Value of l= 0 1 2 3 4…

Symbol/notation for subshell= s p d f g…

So, the notation for different subshells go this way:

n | l | Subshell notation |

1 | 0 | 1s |

2 | 0,1 | 2s, 2p |

3 | 0,1,2 | 3s, 3p, 3d |

So 1

3) Magnetic orbital quantum number, m: It is basically the quantum number assigned to different atomic orbitals present in a subshell. Every atomic orbital has a particular spatial orientation with respect to standard set of co-ordinate axis and this differentiates atomic orbitals within a subshell and every atomic orbital in a subshell is designated with a magnetic quantum number. For a sub-shell defined by value ‘l’, there can be 2l+1 values of ‘m’ i.e. the total no. of orbitals in that subshell can be 2l+1 and their corresponding values of m goes this way: -l to +l.

So, 1

-1,0,+1.

4) Spin quantum number, s: The electrons in an atom has a particle property; it spins on its own axis at a particular speed. The spin quantum number, denoted by s, indicates the orientation of the electron’s angular momentum. It indicates the quantum state, energy, and orbital shape and orientation of the electron. There are only 2 possible values of a spin quantum number are +½ or -½ ( meaning 'spin up' and 'spin down').

On the whole:

Value of l | 0 | 1 | 2 | 3 |

Subshell notation | s | p | d | f |

No. of orbitals | 1 | 3 | 5 | 7 |

Values of m | 0 | -1,0,+1 | -2,-1,0,+1,+2 | -3,-2,-1,0,+1,+2,+3 |

Writing Electronic Configuration

How to write electronic configuration: 3 set of rules govern the writing of electronic configuration. They govern the electronic configuration of all elements. They are:

However, one can write the

So, the order of filling of the electrons goes this way:

1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,4f,5d,6p,7s…

Each atomic orbital can just accommodate only 2 electrons that too in opposite spin only.

So the distribution of electrons goes this way:

n | l | Subshell notation | No. of orbitals | No. of electrons in the subshell | No. of electrons in shell |

1(K) | 0 | 1s | 1 | 2 | 2 |

2(L) | 0 | 2s | 1 | 2 | |

1 | 2p | 3 (2p_{x}, 2p_{y} and 2p_{z}) | 6 | 8 | |

3(M) | 0 | 3s | 1 | 2 | |

1 | 3p | 3 (3p_{x}, 3p_{y} and 3p_{z}) | 6 | ||

2 | 3d | 5 | 10 | 18 |

So, 1

And the order of filling of the electrons in these orbitals are done according to the rules stated above.

Hereby is the electronic configuration chart, showing the electronic configuration of two of the elements:

Figure 1. Electronic configuration of K & F