The electron configuration of an isolated S atom is 2.8.6
or 1S2 1s2 2p6 3s2 3p4
Explanation
Electronic configuration is distribution of electrons of an atom in the atomic orbital.
From the periodic table S atom is in atomic number 16.
The distribution of S electrons is therefore 2.8.6.
The last 6 electrons in 2.8.6 electron configuration are the valence electron which are involved in bonding.