The total number of electrons in a carbon atom is $6$. The distribution of electrons in carbon atom is given by :

First orbit or $K-$ shell $=$ $2$ electrons

Second orbit or $L-$ shell $=$ $4$ electrons

Or, we can write the distribution of electrons in a carbon atom as $2$, $4$.

The total number of electrons in a sodium atom is $11$. The distribution of electrons in sodium atom is given by :

First orbit or $K-$ shell $=$ $2$ electrons

Second orbit or $L-$ shell $=$ $8$ electrons

Third orbit or $M-$ shell $=$$1$ electron

Or, we can write distribution of electrons in a sodium atom as $2$, $8$, $1$.