Question

Name each of the following: a. \(\mathrm{N}_{2} \mathrm{O}_{3}\) b. \(\mathrm{Si}_{2} \mathrm{Br}_{6}\) c. \(\mathrm{P}_{4} \mathrm{~S}_{3}\) d. \(\mathrm{PCl}_{5}\) e. \(\mathrm{N}_{2} \mathrm{~S}_{3}\)

Short answer

a. dinitrogen trioxide, b. disilicon hexabromide, c. tetraphosphorus trisulfide, d. phosphorus pentachloride, e. dinitrogen trisulfide

Step-by-step solution

- Identify the Type of Compound

Determine whether the compounds are covalent (molecular) or ionic. Each of the given compounds consists of nonmetals, which means they are molecular compounds.

- Use the Naming Rules for Molecular Compounds

For molecular compounds, use the prefixes to indicate the number of each element and add 'ide' to the second element's name.

- Naming \(\text{N}_{2}\text{O}_{3}\)

For \(\text{N}_{2}\text{O}_{3}\), the prefix for 2 is 'di' and for 3 is 'tri'. Thus, it is named dinitrogen trioxide.

- Naming \(\text{Si}_{2}\text{Br}_{6}\)

For \(\text{Si}_{2}\text{Br}_{6}\), the prefix for 2 is 'di' and for 6 is 'hexa'. Thus, it is named disilicon hexabromide.

- Naming \(\text{P}_{4}\text{S}_{3}\)

For \(\text{P}_{4}\text{S}_{3}\), the prefix for 4 is 'tetra' and for 3 is 'tri'. Thus, it is named tetraphosphorus trisulfide.

- Naming \(\text{PCl}_{5}\)

For \(\text{PCl}_{5}\), the prefix for 5 is 'penta'. Thus, it is named phosphorus pentachloride.

- Naming \(\text{N}_{2}\text{S}_{3}\)

For \(\text{N}_{2}\text{S}_{3}\), the prefix for 2 is 'di' and for 3 is 'tri'. Thus, it is named dinitrogen trisulfide.

Key concepts

Covalent Compounds

Covalent compounds, also known as molecular compounds, form when two or more nonmetals share electrons to achieve stability. Unlike ionic compounds, which consist of charged ions, covalent compounds are bonded through shared pairs of electrons. This type of bond allows both atoms to fill their outer electron shells. For example, in \(\mathrm{N}_{2} \mathrm{O}_{3}\), nitrogen and oxygen share electrons to form the compound. Covalent bonds are generally characterized by low melting and boiling points compared to ionic compounds. They are also often found in gases or liquids at room temperature.

Prefixes in Chemical Nomenclature

When naming molecular compounds, we use specific prefixes to indicate the number of each type of atom present in the compound. These prefixes help provide a clear structure and avoid confusion. Here are some common prefixes used in chemical nomenclature:

• 1 - mono
• 2 - di
• 3 - tri
• 4 - tetra
• 5 - penta
• 6 - hexa
• 7 - hepta
• 8 - octa
• 9 - nona
• 10 - deca

For instance, in \(\mathrm{Si}_{2} \mathrm{Br}_{6}\), the prefix 'di-' is used for two silicon atoms, and 'hexa-' for six bromine atoms, thus named disilicon hexabromide. The prefix 'mono-' is usually omitted for the first element.

Binary Molecular Compounds

Binary molecular compounds consist of two different nonmetal elements. These compounds are named using the prefix system mentioned above, followed by the name of the first element and then the second element with an 'ide' suffix. This systematic approach removes any ambiguity in the name of the compound.

For example, in \(\mathrm{PCl}_{5}\), phosphorus and chlorine form a binary molecular compound. Here, the prefix 'penta-' indicates five chlorine atoms and the name ends with 'chloride,' making it phosphorus pentachloride. Similarly, \(\mathrm{N}_{2} \mathrm{S}_{3}\) is called dinitrogen trisulfide, with the prefixes 'di-' and 'tri-' indicating their respective quantities, and 'sulfide' denoting the sulfur atom.
By following these naming conventions, identifying and naming binary molecular compounds becomes a straightforward and logical process.