Sulfur, a non-metal element, can form six bonds primarily due to its ability to expand its valence shell. While many elements can only form a limited number of bonds based on the octet rule, sulfur can exceed this limitation because it has access to d-orbitals in its third energy level.
In its most common oxidation states, sulfur typically has 6 valence electrons and can participate in bonding by sharing these electrons. In compounds like sulfur hexafluoride (SF6) or sulfates (SO42-), sulfur shares these electrons with fluorine or oxygen atoms, respectively, allowing it to form six equivalent bonds.
This ability to utilize d-orbitals means that sulfur can accommodate more than 8 electrons in its outer shell, leading to the formation of complex molecules with multiple bonds. Thus, while sulfur typically follows the octet rule in many of its compounds, its unique electronic structure enables it to form six stable bonds in specific chemical contexts.