Question

The compound \(\mathrm{P}_{2} \mathrm{~S}_{5}\) is used to manufacture safety matches. What is the name of this compound?

Short answer

The name of the compound \(\mathrm{P}_{2} \mathrm{~S}_{5}\) is diphosphorus pentasulfide.

Step-by-step solution

Identifying the Elements

Determine which elements are present in the compound. In \(\mathrm{P}_{2} \mathrm{~S}_{5}\), the elements are phosphorus (P) and sulfur (S).

Determining the Prefixes for Naming

Use the Greek prefixes to indicate the number of atoms of each element in the compound. For phosphorus, we have 2 atoms (prefix 'di-'), and for sulfur, we have 5 atoms (prefix 'penta-').

Naming the Compound

Combine the prefixes with the names of the elements in the order they appear. Since the compound ends with a nonmetal (sulfur), the second element's name is slightly altered by adding the suffix '-ide', resulting in 'pentasulfide'. Thus, the compound's name is diphosphorus pentasulfide.

Key concepts

Chemical Nomenclature

Understanding chemical nomenclature is crucial for students studying chemistry as it is the system used for naming chemical substances. Each compound's name carries specific information about its components and structure. In inorganic chemistry, the nomenclature of a compound is typically based on the elements present and their quantities. For example, the compound with the formula \(\mathrm{P}_{2} \mathrm{~S}_{5}\) consists of phosphorus (P) and sulfur (S).

To name such a compound, we first identify the elements involved. Next, we use Greek prefixes to denote the number of atoms of each element present in the molecule. 'Di-' signifies two atoms of phosphorus, and 'penta-' signifies five atoms of sulfur. Lastly, we modify the name of the second non-metal element by adding the suffix '-ide', which helps indicate a binary compound, resulting in 'pentasulfide'. Hence, the complete name becomes diphosphorus pentasulfide.

This systematic approach helps to avoid ambiguities and ensures clear communication in the scientific community. As students progress, they learn that different types of compounds have different nomenclature rules. For covalent compounds, nomenclature becomes even more interesting, as we will see in the following section.

Inorganic Chemistry

Inorganic chemistry involves the study of inorganic compounds, typically those that don't contain carbon-to-carbon bonds. Compounds like \(\mathrm{P}_{2} \mathrm{~S}_{5}\), used in the manufacturing of safety matches, are prime examples of inorganic compounds. Within inorganic chemistry, it's essential to understand the differences between various types of compounds, including ionic compounds, which are held together by ionic bonds, and covalent compounds, which consist of atoms bonded by shared electrons.

In the context of naming inorganic compounds, it's important to note that the rules are varied. Ionic compounds, for instance, are named based on the cation (positive ion) followed by the anion (negative ion), while covalent compounds use prefixes to indicate atom counts, as illustrated in our example. Gaining proficiency in naming compounds in inorganic chemistry serves as the foundation for understanding their properties, behaviors, and reactions. It's a stepping stone to mastering the subject and appreciating the vast world of compounds that interact in our universe.

Covalent Compounds

Covalent compounds are characterized by the sharing of electron pairs between atoms. Unlike ionic bonds that form between metals and non-metals, covalent bonds typically occur between non-metal atoms, creating a vast array of substances from water to DNA. The bond's strength and the molecule's properties are determined in part by the atoms' electronegativities.

A key aspect of understanding covalent compounds is mastering their nomenclature. The correct naming of \(\mathrm{P}_{2} \mathrm{~S}_{5}\), as 'diphosphorus pentasulfide', follows the rules designated for covalent compounds. As seen, the prefixes 'di-' and 'penta-' were derived from Greek to correspond to the number of atoms (two and five, respectively). Furthermore, the application of the suffix '-ide' to the second element's name suggests a compound formed from two non-metals.

For young chemists, recognizing the distinction between covalent and other types of chemical bonds is fundamental to predicting compound properties and behavior. The systematic approach to nomenclature in covalent compounds not only aids in identification but also in understanding the molecular structure and the nuances of chemical bonding.