Negative ions that consist of a single atom are named by adding the suffix ___________ to the stem of the name of the element.
-ide
Understanding Chemical Nomenclature: Naming Single-Atom Negative Ions
In chemistry, naming conventions, or nomenclature, help us identify substances based on their composition. When atoms gain electrons, they become negatively charged ions called anions. Single-atom ions are formed from a single atom.
The question asks for the specific suffix added to the name of an element when it forms a single-atom negative ion. Let's examine the options provided:
- -ous: This suffix is typically used to indicate the lower oxidation state of a metal in older nomenclature (e.g., ferrous chloride for FeCl2 where iron is +2). It is not used for naming single-atom negative ions.
- -ic: This suffix is used to indicate the higher oxidation state of a metal in older nomenclature (e.g., ferric chloride for FeCl3 where iron is +3). Like '-ous', it is not used for naming single-atom negative ions.
- -onium: This suffix is used for certain polyatomic positive ions (cations), such as ammonium (\(\text{NH}_4^+\)) or hydronium (\(\text{H}_3\text{O}^+\)). It is not used for naming single-atom negative ions.
- -ide: This is the standard suffix added to the stem of the element's name to denote a single-atom negative ion. For example:
- Chlorine (\(\text{Cl}\)) forms the chloride ion (\(\text{Cl}^-\)).
- Oxygen (\(\text{O}\)) forms the oxide ion (\(\text{O}^{2-}\)).
- Nitrogen (\(\text{N}\)) forms the nitride ion (\(\text{N}^{3-}\)).
- Sulfur (\(\text{S}\)) forms the sulfide ion (\(\text{S}^{2-}\)).
- Bromine (\(\text{Br}\)) forms the bromide ion (\(\text{Br}^-\)).
Therefore, the suffix used for single-atom negative ions is -ide.
Naming Single-Atom Anions: The -ide Suffix
Let's look at some common examples of how single-atom negative ions are named using the -ide suffix.
| Element | Symbol | Common Ion Formed | Name of Ion |
|---|---|---|---|
| Hydrogen | H | \(\text{H}^-\) | Hydride |
| Fluorine | F | \(\text{F}^-\) | Fluoride |
| Chlorine | Cl | \(\text{Cl}^-\) | Chloride |
| Bromine | Br | \(\text{Br}^-\) | Bromide |
| Iodine | I | \(\text{I}^-\) | Iodide |
| Oxygen | O | \(\text{O}^{2-}\) | Oxide |
| Sulfur | S | \(\text{S}^{2-}\) | Sulfide |
| Nitrogen | N | \(\text{N}^{3-}\) | Nitride |
| Phosphorus | P | \(\text{P}^{3-}\) | Phosphide |
As you can see from the table, the suffix -ide is consistently used for these single-atom negative ions.
Revision Table: Suffixes in Chemical Names
| Suffix | Typical Use | Examples |
|---|---|---|
| -ide | Single-atom negative ions (anions); some polyatomic ions (e.g., hydroxide) | Chloride, Oxide, Sulfide, Hydride, Hydroxide |
| -ous | Lower oxidation state of a metal (historical nomenclature) | Ferrous, Cuprous |
| -ic | Higher oxidation state of a metal (historical nomenclature) | Ferric, Cupric |
| -onium | Certain polyatomic positive ions (cations) | Ammonium, Hydronium |
| -ate | Polyatomic ions containing oxygen (higher number of oxygen atoms) | Sulfate, Nitrate, Carbonate |
| -ite | Polyatomic ions containing oxygen (lower number of oxygen atoms) | Sulfite, Nitrite |
Additional Information on Ion Nomenclature
While -ide is used for single-atom anions, it is also used for a few common polyatomic anions, like hydroxide (\(\text{OH}^-\)), cyanide (\(\text{CN}^-\)), and peroxide (\(\text{O}_2^{2-}\)). However, for most polyatomic oxyanions (ions containing oxygen), suffixes like -ate and -ite are used, indicating different numbers of oxygen atoms bonded to a central atom. Cations (positive ions) formed from metals are simply named after the metal element (e.g., sodium ion \(\text{Na}^+\), calcium ion \(\text{Ca}^{2+}\)). Polyatomic cations have specific names, often ending in -onium, as mentioned earlier.
Understanding these naming rules is crucial for correctly identifying chemical compounds and writing chemical formulas.
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