Question

Name each of the following binary, nonionic compounds: (a) \(\mathrm{NF}_{3}\) (b) HI (c) \(\mathrm{BI}_{3}\) (d) \(\mathrm{PF}_{5}\)

Short answer

(a) Nitrogen trifluoride, (b) Hydrogen iodide, (c) Boron triiodide, (d) Phosphorus pentafluoride.

Step-by-step solution

Naming Binary Nonionic Compounds

Identify the compound as binary and nonionic. Binary nonionic compounds consist of two different nonmetal elements. In such compounds, the element that appears first in the periodic table is named first, followed by the second element with its name modified to end in '-ide.' Greek prefixes are used to indicate the number of each type of atom (except for 'mono-' on the first element).

Name NF3

For \(\mathrm{NF}_{3}\), 'N' is nitrogen and 'F' is fluorine. 'Fluorine' changes to 'fluoride.' Since there is one nitrogen and three fluorines, we name it nitrogen trifluoride.

Name HI

For HI, 'H' is hydrogen and 'I' is iodine. 'Iodine' changes to 'iodide.' As there is one hydrogen and one iodine, this compound is named hydrogen iodide without prefixes.

Name BI3

For \(\mathrm{BI}_{3}\), 'B' is boron and 'I' is iodine, which changes to 'iodide.' Since there are three iodines, the compound is named boron triiodide.

Name PF5

For \(\mathrm{PF}_{5}\), 'P' is phosphorus and 'F' is fluorine, which changes to 'fluoride.' With five fluorines, the compound is named phosphorus pentafluoride.

Key concepts

Greek Prefixes

When naming binary nonionic compounds, Greek prefixes play a vital role. They help indicate the number of atoms of each element present in the compound. With Greek prefixes, you can easily understand the composition of a compound without getting confused.

Here is a quick guide to the most common Greek prefixes used in chemical nomenclature:

• Mono- for 1 (not used for the first element)
• Di- for 2
• Tri- for 3
• Tetra- for 4
• Penta- for 5
• Hexa- for 6
• Hepta- for 7
• Octa- for 8
• Nona- for 9
• Deca- for 10

If a compound like \(\mathrm{NF}_3\) has one nitrogen and three fluorines, we use 'tri-' making it nitrogen trifluoride. Notice that 'mono-' is not used for the nitrogen. This system is used only for nonionic compounds, ensuring precise communication of compound structures.

Periodic Table

The periodic table is a fundamental tool in identifying and naming chemical compounds. Located within it are both metals and nonmetals.

For binary nonionic compounds, we are interested in compounds formed by two nonmetals. In such cases, the element with fewer electrons (the one appearing first in the periodic table) is usually named first. This sequence can be found naturally in compounds like HI, where hydrogen is listed first.

The periodic table not only provides essential information on the elements but also helps in predicting chemical behaviour. It organizes elements based on increasing atomic number and similar chemical properties, which is immensely helpful when trying to understand or predict the type of compound formed.

Chemical Nomenclature

Chemical nomenclature is the systematic naming of chemical compounds based on their composition. Understanding chemical nomenclature is crucial, especially when dealing with nonionic compounds.

For binary nonionic compounds, the name is constructed by:

• Naming the first element as it appears in the periodic table
• Modifying the second element's name to end with '-ide'
• Using Greek prefixes to indicate the number of atoms

In chemical nomenclature, precision is key. This is why, for \(\mathrm{BI}_3\), it is called boron triiodide, where 'tri-' indicates the presence of three iodine atoms, with 'iodine' changing to 'iodide.' This structured approach makes learning and remembering chemical names much easier and less error-prone.

Ionic vs Nonionic Compounds

Chemical compounds can be grouped into two primary categories: ionic and nonionic. Understanding the distinction between them is essential for proper naming and identification.

- **Ionic Compounds** involve a metal and a nonmetal. They form when oppositely charged ions attract each other. Consider sodium chloride (\(\mathrm{NaCl}\)), where sodium (a metal) donates an electron to chlorine (a nonmetal).

- **Nonionic or Covalent Compounds**, like those being named in this exercise, are composed of only nonmetals. Electrons are shared rather than transferred, leading to a more stable relationship. Nonionic compounds use Greek prefixes in their names, as seen in boron triiodide (\(\mathrm{BI}_3\)).

Knowing whether a compound is ionic or nonionic dictates not only its naming conventions but also its chemical behavior. It is the absence of metals in nonionic compounds that leads to different properties and naming rules.