Sulphur

Concept: Chemistry (p-Block Elements) - Allotropes of Sulfur and Molecular Structure.

Step 1: Recall the allotropes of sulfur. Sulfur exists in several allotropic forms, the most common being rhombic sulfur ( -sulfur) and monoclinic sulfur ( -sulfur). Both of these stable crystalline forms consist of molecules.

Step 2: Determine the molecular shape of the molecule. In an molecule, eight sulfur atoms are covalently bonded to each other to form a closed ring. However, to minimize steric hindrance and electronic repulsion, the ring is not planar. It adopts a puckered shape, commonly referred to as a "crown" shape.

Step 3: Identify the hybridization of the sulfur atoms. Each sulfur atom in the ring is bonded to two other adjacent sulfur atoms and has two lone pairs of electrons. This corresponds to an hybridization state, which normally has a tetrahedral bond angle of .

Step 4: Consider lone pair-lone pair repulsions. According to VSEPR theory, lone pair-lone pair repulsions are greater than bond pair-bond pair repulsions. The presence of two bulky lone pairs on every single sulfur atom pushes the S-S bonds slightly closer together, reducing the bond angle from the ideal .

Step 5: State the experimentally determined bond angle. X-ray crystallography and structural studies have precisely measured the dimensions of the puckered crown ring. The uniform S-S bond length is exactly 204 pm, and the S-S-S bond angle is compressed to exactly . Comparing this fixed structural property with the given options confirms that is the correct value. $ $