Question

Sulfur is known in many forms, including yellow sulfur (formula \(\mathrm{S}_{8}\) ) and orange-red sulfur (formula \(\mathrm{S}_{6}\) ). Heating either of these forms to very high temperatures can yield \(\mathrm{S}_{2}\). Also known is a substance with the formula \(\mathrm{SO}_{2}\). Since all of these substances are made of elements, are they all elemental substances? Explain.

Short answer

The S8, S6, and S2 forms of sulfur are elemental substances because they consist of only one type of atom (sulfur). However, the SO2 molecule is not an elemental substance as it contains two different types of atoms (sulfur and oxygen).

Step-by-step solution

Understanding an elemental substance

An elemental substance is a pure substance that consists of only one type of atom. For example, oxygen (O2) and nitrogen (N2) are elemental substances because they are made up of only one type of atom (oxygen and nitrogen, respectively).

Examining Sulfur Molecules (S8, S6, and S2)

We are given three forms of sulfur molecules: Yellow sulfur (S8), orange-red sulfur (S6), and a high-temperature form (S2). In all these forms, the molecules consist of only sulfur atoms. So, these can be considered as elemental substances.

Examining the SO2 Molecule

The last molecule given is SO2. This molecule consists of one sulfur atom (S) and two oxygen atoms (O2). Since it contains two different types of atoms (sulfur and oxygen), this molecule is not an elemental substance.

Conclusion

Based on our analysis, we can conclude that the S8, S6, and S2 forms of sulfur are elemental substances because they consist of only one type of atom (sulfur). However, the SO2 molecule is not an elemental substance as it contains two different types of atoms (sulfur and oxygen).

Key concepts

Sulfur Allotropes

Elemental sulfur exists in different forms, known as allotropes. Think of allotropes as different family members that have unique characteristics, though they share the same genetic makeup—in this case, sulfur atoms.

The yellow sulfur with the formula \( \text{S}_8 \) is the most common and stable allotrope of sulfur, widely recognized for its bright yellow crystals. The molecule forms a ring structure, with each sulfur atom bonded to two other sulfur atoms. Similarly, orange-red sulfur, which has the formula \( \text{S}_6 \), is another allotrope with a distinct ring structure, but with six sulfur atoms. These allotropes differ in physical properties like color and crystalline form but are chemically similar because they are made solely of sulfur.

When yellow or orange-red sulfur is heated to very high temperatures, it can produce \( \text{S}_2 \), consisting of two sulfur atoms. All these forms are elemental because they are pure sulfur, just in different structural configurations. This concept is key in understanding the diversity within an element's forms and is a perfect illustration of the dynamic nature of chemical structures.

Chemical Formulas

Chemical formulas serve as a shorthand to convey detailed information about the composition of a substance. They are like recipes listing ingredients: elements are symbols from the periodic table, and subscripts tell you how many atoms of each are present.

In the case of the sulfur allotropes, \( \text{S}_8 \) means eight sulfur atoms connected in a ring, and \( \text{S}_6 \) means six sulfur atoms in a different ring arrangement. The subscript represents the number of atoms in a molecule, which can indicate the molecule's structure, stability, and sometimes even its appearance. Understanding chemical formulas is critical when studying chemistry because they are a universal language that scientists use to describe substances and their transformations. Deciphering these formulas gives insight into the world of atoms and their interactions.

Elemental vs Compound Substances

The distinction between elemental and compound substances is like differentiating a single pure breed dog from a mixed breed. Elemental substances are the pure breeds, consisting of a single type of atom, while compound substances are the mixed breeds, containing more than one type of atom chemically bonded together.

Taking sulfur as an example, \( \text{S}_8 \), \( \text{S}_6 \), and \( \text{S}_2 \) are all elemental substances because they are pure sulfur, regardless of the number of atoms bonded together. In contrast, a substance like \( \text{SO}_2 \) is a compound because it contains sulfur and oxygen bonded together. This compound, known as sulfur dioxide, has distinct chemical and physical properties that are different from those of elemental sulfur. Recognizing whether a substance is elemental or a compound is fundamental in chemistry, as it dictates how a substance behaves, reacts, and how it can be transformed in chemical reactions.