6.5: Naming Ionic Compounds
- Page ID
- 366505
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Given the formula of an ionic compound (which may contain a fixed-charge or variable-charge metal and may contain a polyatomic ion) write the name.
Naming Binary Ionic Compounds with a Metal that Forms Only One Type of Cation
A binary ionic compound is a compound composed of a monatomic metal cation and a monatomic nonmetal anion. The metal cation is named first, followed by the nonmetal anion as illustrated in Figure \(\PageIndex{1}\) for the compound BaCl2. The word ion is dropped from both parts.
Subscripts in the formula do not affect the name.
Name each ionic compound.
- CaCl2
- AlF3
- KCl
Solution
- Using the names of the ions, this ionic compound is named calcium chloride.
- The name of this ionic compound is aluminum fluoride.
- The name of this ionic compound is potassium chloride
Name each ionic compound.
- AgI
- MgO
- Ca3P2
- Answer a:
- silver iodide
- Answer b:
- magnesium oxide
- Answer c:
- calcium phosphide
Naming Binary Ionic Compounds with a Metal That Forms More Than One Type of Cation
If you are given a formula for an ionic compound whose cation can have more than one possible charge, you must first determine the charge on the cation before identifying its correct name. For example, consider FeCl2 and FeCl3 . In the first compound, the iron ion has a 2+ charge because there are two Cl− ions in the formula (1− charge on each chloride ion). In the second compound, the iron ion has a 3+ charge, as indicated by the three Cl− ions in the formula. These are two different compounds that need two different names. The names are iron(II) chloride and iron(III) chloride (Figure \(\PageIndex{2}\)).
Name of cation (metal) + (Roman Numeral in parenthesis) + Base name of anion (nonmetal) and -ide | |
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Figure \(\PageIndex{2}\): Naming Ionic Compounds with Variable Charge Metals
Name each ionic compound.
- Co2O3
- FeCl2
Solution
Explanation | Answer | |
---|---|---|
a |
We know that cobalt can have more than one possible charge; we just need to determine what it is.
|
cobalt(III) oxide |
b |
Iron can also have more than one possible charge.
|
iron(II) chloride |
Name each ionic compound.
- AuCl3
- PbO2
- CuO
- Answer a:
- gold(III) chloride
- Answer b:
- lead(IV) oxide
- Answer c:
- copper(II) oxide
Naming Ionic Compounds with Polyatomic Ions
The process of naming ionic compounds with polyatomic ions is the same as naming binary ionic compounds. The cation is named first, followed by the anion. One example is the ammonium sulfate compound in Figure \(\PageIndex{6}\).
Write the proper name for each ionic compound.
- (NH4)2S
- AlPO4,
- Fe3(PO4)2
Solution
Explanation | Answer |
---|---|
a. The ammonium ion has a 1+ charge and the sulfide ion has a 2− charge. Two ammonium ions need to balance the charge on a single sulfide ion. The compound’s name is ammonium sulfide. |
ammonium sulfide |
b. The ions have the same magnitude of charge, one of each (ion) is needed to balance the charges. The name of the compound is aluminum phosphate. |
aluminum phosphate |
c. Neither charge is an exact multiple of the other, so we have to go to the least common multiple of 6. To get 6+, three iron(II) ions are needed, and to get 6−, two phosphate ions are needed . The compound’s name is iron(II) phosphate. |
iron(II) phosphate |
Write the proper name for each ionic compound.
- (NH4)3PO4
- Co(NO2)3
- Answer a:
- ammonium phosphate
- Answer b:
- cobalt(III) nitrite
Figure \(\PageIndex{1}\) is a synopsis of how to name simple ionic compounds.
![3.7.jpg](https://chem.libretexts.org/@api/deki/files/28852/3.7.jpg?revision=1&size=bestfit&width=783&height=414)
Name each ionic compound.
- ZnBr2
- Al2O3
- (NH4)3PO4
- AuF3
- AgF
- Answer a:
- zinc bromide
- Answer b:
- aluminum oxide
- Answer c:
- ammonium phosphate
- Answer d:
- gold(III) fluoride
- Answer e:
- silver fluoride
Contributions & Attributions
This page was constructed from content via the following contributor(s) and edited (topically or extensively) by the LibreTexts development team to meet platform style, presentation, and quality:
Henry Agnew (UC Davis)