Is Sulfur Diatomic? (+ 3 Surprising Facts to Know)

No, sulfur is not diatomic at standard temperature and pressure (STP). At STP, sulfur exists as a solid composed of S8 molecules, which are octatomic and ring-shaped. ¹

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Why is sulfur octatomic?

Sulfur is a chemical element that can exist in several different forms, or allotropes, depending on the conditions under which it is prepared. ² One of these allotropes is S8, which consists of eight sulfur atoms arranged in a ring structure. This form of sulfur is commonly known as “octatomic sulfur” or “cyclic sulfur” because of its eight-atom ring structure.

The reason why sulfur tends to form S8 molecules is because of the stability that arises from the ring structure. The sulfur atoms in the ring are held together by covalent bonds, which are relatively strong and stable. ³

Additionally, the ring structure allows for the sulfur atoms to be arranged in a way that minimizes repulsive forces between the negatively charged electrons in the outer shells of the atoms. This arrangement of atoms and electrons maximizes the stability of the molecule.

It’s also worth noting that S8 sulfur is not the only form of sulfur that exists. Other allotropes, such as S2 and S6, are also known to exist under certain conditions. ^{4 5}

These allotropes have different structures and properties than S8 sulfur, but they are less common and less stable than the octatomic form.

Does diatomic sulfur exist?

Yes, diatomic sulfur (S2) does exist, but it is not the most stable form of sulfur. S2 is a transient species that can be formed in high-temperature chemical reactions or in the gas phase. ^{6 7 8 9}

At room temperature and normal atmospheric pressure, sulfur typically exists in its most stable molecular form, S8, which consists of eight sulfur atoms arranged in a ring. 

It’s important to note that S2 is not the same as elemental sulfur (S), which consists of individual sulfur atoms rather than diatomic molecules.

How do sulfur atoms bond to form an octatomic molecule?

In the formation of an S8 molecule, each sulfur atom contributes six valence electrons to form a covalent bond with two adjacent sulfur atoms. ¹⁰ This results in the formation of a ring structure with each sulfur atom having two covalent bonds with its neighboring sulfur atoms. 

The electron configuration of sulfur allows for the formation of these covalent bonds by sharing electrons between the atoms to achieve a stable octet configuration. ¹¹

Specifically, the sulfur atoms bond together through the sharing of pairs of electrons in their outermost energy level, known as the valence shell. 

Each sulfur atom has six valence electrons in its outer shell, and by sharing two electrons with each of its two neighboring sulfur atoms, each sulfur atom can complete its valence shell with a total of eight electrons, thus forming a stable octatomic molecule. 

The resulting S-S bond is a covalent bond, meaning that the electrons are shared between the sulfur atoms. In an S8 molecule, each sulfur atom is bonded to two neighboring sulfur atoms, resulting in a total of six S-S bonds in the ring structure.

Further reading

Why is Iodine Diatomic?
Why is Chlorine Diatomic?
Is Nitrogen a Compound?
Is Oxygen a Compound?
Is Oxygen a Mixture? 

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