Sulfur is a non-metal element known for its distinctive yellow color and role in industrial processes, such as sulfuric acid production and vulcanizing rubber. To understand which other elements share its properties, the structure of the Periodic Table provides the answer. Elements are arranged in vertical columns, or groups, based on their chemical behavior. Elements within the same group possess similar characteristics, meaning any element found directly above or below sulfur will exhibit a distinct chemical kinship.
Sulfur’s Chemical Family: The Chalcogens
The family of elements that includes sulfur is found in Group 16 of the Periodic Table and is collectively known as the Chalcogens. This group includes Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po), along with the synthetic element Livermorium (Lv).
The most direct chemical relatives to sulfur are the elements immediately below it: Selenium (Se) and Tellurium (Te). These elements are the most commonly cited examples mirroring sulfur’s chemical properties. Moving down the group, the elements become progressively more metallic in character. Oxygen, the first member, displays unique behavior due to its small size and high electronegativity, making its chemistry less analogous to sulfur’s than the heavier elements.
The Basis of Similarity: Valence Electrons
The reason for this shared chemistry lies in the arrangement of electrons in the outermost shell, known as valence electrons. All Chalcogen elements, including sulfur, possess six valence electrons in their outermost shell. This specific number of valence electrons dictates how an element will interact with others in a chemical reaction.
Group 16 atoms aim to achieve a stable octet, which is a full complement of eight electrons in the outer shell. To reach this stability, they tend to gain two electrons, resulting in a common oxidation state of \(-2\) when forming simple ionic compounds with metals. Heavier elements like sulfur, selenium, and tellurium also have accessible \(d\)-orbitals. This allows them to expand their valence shell beyond eight electrons, enabling higher oxidation states such as \(+4\) and \(+6\).
Comparing Chemical Behaviors
The shared six-valence-electron structure leads to similar and predictable chemical behaviors across the Chalcogen family. A primary parallel is their ability to form analogous compounds with hydrogen. Sulfur forms hydrogen sulfide (\(H_2S\)), which is mirrored by hydrogen selenide (\(H_2Se\)) and hydrogen telluride (\(H_2Te\)). All three share a bent molecular geometry.
Sulfur, selenium, and tellurium exhibit a shared range of oxidation states, commonly forming compounds in the \(-2\), \(+4\), and \(+6\) states. They form oxides with the formula \(EO_2\), such as sulfur dioxide (\(SO_2\)) and selenium dioxide (\(Se_2\)). Their highest oxidation state is represented in trioxides, like sulfur trioxide (\(SO_3\)). These elements also form similar oxyacids; sulfuric acid (\(H_2SO_4\)) has a direct counterpart in selenic acid (\(H_2SeO_4\)), and both are strong acids.
The tendency to form halides, or compounds with halogens, also runs parallel through the group, such as the formation of hexafluorides like sulfur hexafluoride (\(SF_6\)). Any compound sulfur forms is likely to have a selenium or tellurium analogue. Although the stability of the highest oxidation state decreases from sulfur to tellurium, the overall chemical blueprint remains consistent.