Here's why:

* Electronegativity: Sulfur has an electronegativity of 2.58. This means it doesn't attract electrons strongly enough to form ionic bonds.

* Sharing Electrons: Instead, sulfur atoms share electrons with each other to achieve a stable octet (8 electrons) in their outer shell. This shared electron arrangement creates a covalent bond.

Sulfur exists in various allotropes (different forms of the same element) with different structures:

* S8 (Octasulfur): The most common form, consisting of a ring of eight sulfur atoms linked by single covalent bonds.

* S6 (Hexasulfur): A less stable ring of six sulfur atoms.

* S2 (Disulfur): A diatomic molecule like oxygen, formed at high temperatures.

Important Note: While sulfur forms covalent bonds with itself, it can also form covalent bonds with other nonmetals, like oxygen in sulfur dioxide (SO2) or hydrogen in hydrogen sulfide (H2S).