Introductory Chemistry: A Foundation - Zumdahl S.S., DeCoste D.J. 2019

Nomenclature
Naming Binary Compounds That Contain Only Nonmetals (Type III)

Objective

· To learn how to name binary compounds containing only nonmetals.

Binary compounds that contain only nonmetals are named in accordance with a system similar in some ways to the rules for naming binary ionic compounds, but there are important differences. Type III binary compounds contain only nonmetals. The following rules cover the naming of these compounds.

Rules for Naming Type III Binary Compounds

1. The first element in the formula is named first, and the full element name is used.

2. The second element is named as though it were an anion.

3. Prefixes are used to denote the numbers of atoms present. These prefixes are given in Table 5.3.

Table 5.3. Prefixes Used to Indicate Numbers in Chemical Names

Prefix

Number Indicated

mono-


di-


tri-


tetra-


penta-


hexa-


hepta-


octa-


4. The prefix mono- is never used for naming the first element. For example, is called carbon monoxide, not monocarbon monoxide.

We will illustrate the application of these rules in Example 5.4.

Interactive Example 5.4. Naming Type III Binary Compounds

Name the following binary compounds, which contain two nonmetals (Type III).

a.

b.

c.

Solution

a.

Rule 1

Name the first element, using the full element name: boron.

Rule 2

Name the second element as though it were an anion: fluoride.

Rules 3 and 4

Use prefixes to denote numbers of atoms. One boron atom: do not use mono- in the first position. Three fluorine atoms: use the prefix tri-.

b. The name of is boron trifluoride.

c.

Compound

Individual Names

Prefixes

Comments


nitrogen

none

Mono- is not used for the first element.


oxide

mono-


d. The name for is nitrogen monoxide. Note that the second o in mono- has been dropped for easier pronunciation. The common name for , which is often used by chemists, is nitric oxide.

e.

Compound

Individual Names

Prefixes

Comments


nitrogen

di-

two atoms


oxide

penta-

five atoms

f. The name for is dinitrogen pentoxide. The a in penta- has been dropped for easier pronunciation.

g.

h. © Cengage Learning

i. A piece of copper metal about to be placed in nitric acid (left). Copper reacts with nitric acid to produce colorless (which immediately reacts with the oxygen in the air to form reddish-brown gas) and ions in solution (which produce the green color) (right).

Self-Check: Exercise 5.3

· Name the following compounds.

a.

b.

c.

See Problems 5.17 and 5.18.

The previous examples illustrate that to avoid awkward pronunciation, we often drop the final o or a of the prefix when the second element is oxygen. For example, is called dinitrogen tetroxide, not dinitrogen tetraoxide, and is called carbon monoxide, not carbon monooxide.

Some compounds are always referred to by their common names. The two best examples are water and ammonia. The systematic names for and are never used.

To make sure you understand the procedures for naming binary nonmetallic compounds (Type III), study Example 5.5 and then do Self-Check Exercise 5.4.

Interactive Example 5.5. Naming Type III Binary Compounds: Summary

Name each of the following compounds.

a.

b.

c.

d.

e.

f.

Solution


Compound

Name

a.


phosphorus pentachloride

b.


tetraphosphorus hexoxide

c.


sulfur hexafluoride

d.


sulfur trioxide

e.


sulfur dioxide

f.


dinitrogen trioxide

Self-Check: Exercise 5.4

· Name the following compounds.

a.

b.

c.

See Problems 5.17 and 5.18.