The following is a summary of the rules for naming simple compounds. Use the menu bar at the left to navigate through the page.

The first step in naming a compound involves identifying what sort of compound it is.

• Ionic: These will consist of elements from opposite sides of the periodic table. They are further subdivided into three types for nomenclature purposes.

  • Binary Ionic (Type I): These consist of a group 1 (Li, Na, K, etc)or group 2 metal cation Mg, Ca, Sr, etc.) combined with another element. These cations have a fixed charge (group 1 is +1 and group 2 is +2)

  • Binary Ionic (Type II): These consist of a metal cations (often transition metals) that may exhibit a number of different oxidations states. (examples Cu, V, Pb ) combined with one other element.

  • Polyatomic Ionic: These compounds contain polyatomic ions. You must be able to recognize a polyatomic ion (examples NH₄^{+, SO₄2- in NH₄Cl and Na₂SO₄)}

• Binary Molecular: These compounds contain two non-metallic elements (S and O, N and Cl, etc.)

• Acids: these compounds must contain a Hydrogen that is can easily dissociate

  • Binary Acids: These consist of hydrogen bonded to a group 7 anion (over simplfied) and dissolved in water. (examples: aqueous solutions of HF, HCl, HBr, and HI)

  • Oxyacids: These compounds have hydrogen bonded to the oxygen of a polyatomic ion. (examples HNO₃, H₂SO_{3, etc...)}

 Binary Ionic Compounds (Type I)  

	Cation is named first and the anion second
	Cation keeps its elemental name (Ca2+ is called calicium)
	Anion is named by taking the root of the element name and adding -ide
	Examples: CsI Cesium Iodide CaO Calcium Oxide Na2Se Sodium Selenide

 Binary Ionic Compounds (Type II)  

	Cation is named first and the anion second
	The charge of the cation depends on the charge of the anion. As a result it must be specified in the name. Note that certain cations will have only one charge (Ag(I), Al(III), Zn(II), Cd(II)) and the charge does not need to be specified
	Cation keeps its elemental name but the charge is designated by adding the appropriate roman numerals within parantheses at the end of the cation name
	Anion is named by taking the root of the element name and adding -ide
	An older system which is still sometimes used involves the use of -ous and -ic endings to designate the lower charged ion and the higher charged cation. These endings are added to the original names shown in Zumdahl table 2.2. (don't need for exam but its good to know)
	Examples: FeBr2 Iron(II) Bromide (Ferrous Bromide) FeBr3 Iron(III) Bromide (Ferric Bromide) MnO2 Manganese(IV) Oxide

 Ionic Compounds with Polyatomic Ions

	Cation is named first and the anion second
	Use names of the polyatomic ions. These MUST be memorized.
	For oxyanions (those containing and element + oxygen) the following prefixes and suffixes are added to the root Only 2 oxyanions present for an element least oxygens -ite most oxygens -ate For Cl, Br, I oxyanions one oxygen: hypo- and -ite two oxygens: -ite three oxygens: -ate four oxygens: per- and -ate
	Examples: LiClO or LiOCl Lithium Hypochlorite Ca(ClO2)2 Calcium Chlorite KClO3 Potassium Chlorate Ba(ClO4)2 Barium Perchlorate

 Binary Molecular (two elements near one another on the periodic table)

	Least electronegative element is named first (the element closest to the lower left of the periodic table)
	Greek prefixes (di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-) are added to the element name to indicate the number of atoms present
	Mono- is never used for naming the first element
	Examples: CO Carbon Monoxide PF5 Phosphorous Pentaflouride N2O Dinitrogen Monoxide

 Binary Acids (Hydrogen with No Oxygen)

	Add prefix hydro- and the suffix -ic to the anion root name
	Add the word acid to the end of the name
	Note that this system requires that the molecule is dissolved in water (aqueous solution). Otherwise its treated like a molecular compound.
	Examples: (assuming aqueous soln) HF hydroflouric acid HCN hydrocyanic acid HI hydroiodic acid

 Oxyacids (Hydrogen bonded to Oxygen)

	If the Anion name ends in -ate replace it with the suffix -ic
	If the Anion name ends in -ite replace it with the suffix -ous
	Add the word acid to the end of the name
	Keep any prefixes such as hypo- and per-
	Examples: HClO or HOCl Hypochlorous Acid HClO2 Chlorous HClO3 Chloric Acid HClO4 Perchloric Acid

 

 

 

---

Bridgewater Homepage

Chemistry Homepage

Search Bridgewater

Search Chemistry Pages

---

E-mail: shaefner@bridgew.edu
The number of times this page has been accessed: 
Created 08/12/02
Last Modified: