What is the electron configuration of an isolated s atom?

Sulfur possesses 16 electrons in its ground state. The first shell of sulfur has 2 electrons. The next shell has 8 electrons. The third and final shell of sulfur has 6 electrons. The electronic configuration is written as:

1s², 2s², 2p⁶, 3s², 3p⁴

This means that sulfur exhibits a valency of - 2, which is true in many cases.