Question

Name each of the following binary compounds, using the periodic table to determine whether the compound is likely to be ionic (containing a metal and a nonmetal) or nonionic (containing only nonmetals). a. \(\mathrm{MgS}\) b. \(\mathrm{AlCl}_{3}\) c. \(\mathrm{PH}_{3}\) d. \(ClBr\) e. \(L i_{2} O\) f. \(P_{4} O_{10}\)

Short answer

a. Magnesium sulfide (ionic) b. Aluminum chloride (ionic) c. Phosphorus trihydride (nonionic) d. Chlorine monobromide (nonionic) e. Lithium oxide (ionic) f. Tetraphosphorus decioxide (nonionic)

Step-by-step solution

Understand the naming rules for ionic and nonionic compounds

Ionic compounds consist of a metal and a nonmetal. They are named by writing the name of the metal first, followed by the name of the nonmetal with its ending changed to -ide. Nonionic compounds contain only nonmetals. They are named using a prefix system based on the number of atoms of each element in the compound. The prefix mono- is omitted for the first element, and if there is only one atom of the second element, then the prefix mono- is used before the second element's name, with -ide as the ending.

Name each compound and determine its type

a. \(\mathrm{MgS}\) - Magnesium (Mg) is a metal, and Sulfur (S) is a nonmetal. This is an ionic compound named Magnesium sulfide. b. \(\mathrm{AlCl}_{3}\) - Aluminum (Al) is a metal, and Chlorine (Cl) is a nonmetal. This is an ionic compound named Aluminum chloride. c. \(\mathrm{PH}_{3}\) - Phosphorus (P) and Hydrogen (H) are both nonmetals. This is a nonionic compound named Phosphorus trihydride. d. \(ClBr\) - Chlorine (Cl) and Bromine (Br) are both nonmetals. This is a nonionic compound named Chlorine monobromide. e. \(L i_{2} O\) - Lithium (Li) is a metal, and Oxygen (O) is a nonmetal. This is an ionic compound named Lithium oxide. f. \(P_{4} O_{10}\) - Phosphorus (P) and Oxygen (O) are both nonmetals. This is a nonionic compound named Tetraphosphorus decioxide.

Key concepts

Ionic Compounds

Ionic compounds are formed when atoms transfer electrons from one to another, resulting in the creation of ions. The allure of ionic bonding comes from the attraction between positively charged metal ions and negatively charged nonmetal ions. This type of bonding is characteristic between a metal and a nonmetal.
For example, in the compound \( \text{MgS} \), magnesium (Mg) gives up electrons to become a positively charged ion, while sulfur (S) gains those electrons to become a negatively charged ion. This exchange produces magnesium sulfide, an ionic compound.

• These compounds are generally hard and brittle.
• Ionic compounds typically have high melting and boiling points.
• When dissolved in water, they conduct electricity because the ions are free to move.

Recognizing the metal and nonmetal combination in a binary compound often indicates an ionic nature. The naming convention for ionic compounds is straightforward: name the metal first, then the nonmetal with an '-ide' suffix, like 'chloride' or 'oxide'.

Nonionic Compounds

Nonionic compounds, also known as covalent compounds, are formed when atoms share electrons. This sharing typically occurs between nonmetals. In nonionic compounds, there are no charged ions, and thus, the compounds do not conduct electricity.
For instance, \( \text{PH}_3 \) consists of phosphorus and hydrogen, both of which are nonmetals. The atoms share electrons, forming phosphorus trihydride, a nonionic compound.
Characteristics of nonionic compounds include:

• They often have lower melting and boiling points compared to ionic compounds.
• They can exist in all three physical states: solid, liquid, or gas, at room temperature.
• These compounds do not conduct electricity as they lack free-moving ions.

The naming system for nonionic compounds involves prefixes like mono-, di-, tri- to indicate the number of atoms, with '-ide' added to the end of the second element's name.

Naming Chemical Compounds

Naming chemical compounds correctly is crucial for clear scientific communication. Each type of compound—ionic or nonionic—has its unique naming system.
For ionic compounds, the metal's name appears first, followed by the nonmetal with an '-ide' suffix. No numerical prefixes are needed because the charges on the ions predictably set the compound's formula, ensuring the total charge is zero. Examples include magnesium sulfide (\(\text{MgS}\)) and aluminum chloride (\(\text{AlCl}_3\)).
In contrast, nonionic compounds use numerical prefixes to indicate the number of each type of atom present in the compound. The prefixes are based on Latin numbers: one is mono-, two is di-, three is tri-, and so on. The exception is that mono- is usually omitted for the first element. Examples include tetraphosphorus decioxide (\(\text{P}_4\text{O}_{10}\)) and chlorine monobromide (\(\text{ClBr}\)).
By following these systems, chemists can accurately describe a compound's composition without ambiguity. This understanding not only promotes effective communication but also aids in predicting and explaining compound behavior.