Question

Can someone explain me how the electrons are distributed in an atom of any element above atomic number 20 . Please tell me the rules and explain .

Answer 1

The rule 2n^2 gives the max number of electrons a particular shell in an atom can accomodate. N is the shell number, e.g. 1st shell, 2 shell... The no. of electrons in an atom is equal to it's atomic no. Once a shell is full of electrons, start filling the next shell. E.g. Carbon- Atomic no.=6. 1st shell can contain only 2 electrons, so we go to the next shell. Four electrons remain and we put them in the 2nd shell.

Answer 2

Hey Friend !



Shells of an atom:

K shell
L shell
M shell
N shell
etc ....


Rules followed for the distribution of electrons in an atom :-


1) The maximum number of electrons present in a shell is given by the formula 2n², where ‘n’ is the orbit number or energy level
K shell = 2n² = 2 × 1² = 2 electrons
L shell = 2n² = 2 × 2² = 8 electrons

etc......

2)The maximum number of electrons that can be accommodated in the outermost orbit is 8.

3)Electrons are not accommodated in a given shell, unless the inner shells are filled. Which means that , the shells are filled in a step-wise manner.

K shell can hold a maximum of two electrons
L shell can hold a maximum of 8 electrons
M shell can hold a maximum of 18 electrons and
N shell a maximum of 32 electrons

Even though , the M shell has the capacity to hold 18 electrons , it can't hold more than eight electrons.
Hence , as soon as the number of electrons in the M shell exceeds eight.
The next shell , that is , the N shell gets filled.

Hence , electronic configuration of the element with atomic number 20 is :-
2 , 8 , 8 , 2