Question

Oxygen forms double bonds in${\mathrm{O}}_2$, but sulfur forms single bonds in ${\mathrm{S}}_8$. Why?

Short answer

Due to its size, S-S $\pi$ bonds are not possible.

Step-by-step solution

To explain the oxygen forms double bonds in ${\mathrm{O}}_2$, but sulfur forms single bonds in ${\mathrm{S}}_8$. why?

Sulfur atoms are larger than the oxygen atoms and have an empty d orbital. Because of this reasons, sulfur atoms are not able to form S-S double bonds or$\pi$ bonds which oxygen atoms.

The double bond formed by Sulfur is due to the size of it as an atom which is bigger than that of an oxygen atom.