Fill in the blank.
The name of the ionic compound Al2O3 is
The name of the ionic compound Na2SO4 is
Naming Covalent Compounds
Chemists name binary covalent compounds using prefixes and suffixes attached to root words. Each of these parts has a meaning and conveys information about the composition of the compound. The first element in the formula is named first using the full element name. The second element is named second using the suffix “-ide” attached to the root word for the element’s name.
An example is diphosphorus pentoxide, the name for the covalent compound with the chemical formula, P2O5. The prefix “di-“ in front of the root word “phosphorus” means that there are two phosphorus atoms in the compound. The prefix “pent” in front of the root word “ox“ means that there are five oxygen atoms in the compound. The suffix “-ide” is placed on the end of the names of most compounds to indicate that the elements are combined in a compound. Note that hydrocarbons follow different rules for naming them.
The prefixes used in covalent compound names indicate the number of each element in that compound. Table 4 shows these prefixes. Each prefix indicates a specific number. The prefix “mono-“ is omitted anytime it would appear as the first prefix in a name. For example, carbon dioxide is the covalent compound with the chemical formula CO2. This compound could be named monocarbon dioxide according to the system described above. However, the “mono-“ prefix is dropped since it is the first prefix in the name, and the compound is named carbon dioxide.
The prefix “mono-“ is used when it appears at places other than first in a compound’s name. For example, the compound with chemical formula CO is named carbon monoxide to distinguish it from CO2.
Note that the final vowels “o” and “a” of the above prefixes are often dropped when the root word of the element begins with a vowel. For example, “monooxide” is written as monoxide and “tetraoxide” is written as tetroxide.
