Question

State the suffix in the name for each of the following: (a) NaI (b) \(\mathrm{HI}(a q)\)

Short answer

(a) Iodide for NaI. (b) Iodic for HI(aq).

Step-by-step solution

- Determine the Suffix for NaI

Sodium iodide (NaI) is a compound formed from the sodium cation ( ext{Na}^+) and iodide anion ( ext{I}^-). In chemical naming for binary ionic compounds, the anion is named by taking the root of the element and adding the suffix '-ide'. Since iodine's root is 'iod-', the suffix is '-ide'. Thus, NaI is named Sodium iodide.

- Determine the Suffix for HI(aq)

The compound \( ext{HI (aq)}\) refers to hydroiodic acid. This is an aqueous solution of hydrogen iodide. In naming acids where the anion ends in '-ide', the suffix changes to '-ic' with the prefix 'hydro-' added to the name. Iodide becomes 'iodic' as the suffix for the acid, and thus \( ext{HI (aq)}\) is named hydroiodic acid.

Key concepts

Binary Ionic Compounds

Binary ionic compounds consist of two different elements: one is a metal, and the other is a non-metal. These compounds are so named because they are 'binary' (composed of two elements) and 'ionic' (involving ions). The metal in the compound loses electrons to become a cation, whereas the non-metal gains electrons to become an anion.
The naming of binary ionic compounds is simple once you understand the pattern. First, the name of the metal, which is the cation, is stated first and stays unchanged. Then, the name of the non-metal follows, but with a significant change: its ending is replaced by the suffix '-ide'. For example, in sodium iodide (NaI), 'sodium' is the cation and remains unchanged, but 'iodine' has its ending replaced to 'iodide'.
The logic behind naming binary ionic compounds helps in identifying both the elements involved and their states (cation or anion). By learning these basic patterns, students can easily name any straightforward binary ionic compound.

Acid Naming

Chemical nomenclature for acids involves a slightly different set of rules compared to ionic compounds. Acids often start their formulas with hydrogen (H), signaling that they release hydrogen ions ( ext{H}^+) when dissolved in water. The naming of the acid varies depending on the anion attached to the hydrogen.
When the anion does not contain oxygen, and ends in '-ide', the acid name begins with the prefix 'hydro-', follows with the root of the anion's name, and ends with the suffix '-ic acid'. For example, hydrogen iodide becomes hydroiodic acid when in aqueous form, as seen in the chemical formula ext{HI}(aq). This pattern helps distinguish which acid is being referred to based on its components.
Understanding these naming conventions is crucial in chemistry because it enables you to decipher the chemical formula of a compound simply from hearing or reading its name.

Ionic Compound Suffixes

Suffixes in chemical nomenclature help in identifying the nature and composition of ionic compounds and acids. The most common suffix for binary ionic compounds is '-ide'. This suffix signifies that the compound consists of a metal cation and a simple non-metal anion. For instance, the suffix '-ide' in sodium iodide indicates that iodine is the non-metal anion combined with sodium.
When it comes to naming acids, the suffix changes if the acid involves an anion ending in '-ide'. Such compounds adopt the '-ic' suffix, highlighting their acidic nature. Hydroiodic acid, derived from hydrogen iodide, illustrates this transition, as the original '-ide' ending is transformed to '-ic'.
These suffixes are integral to understanding and naming compounds correctly. By recognizing these subtle yet significant changes, you can accurately determine the type of compound and communicate its identity effectively.