Lecture: Naming Compounds and the Mole Concept
Naming Compounds and the Mole Concept Review
Compound Naming Review
All compounds must be neutral, meaning the sum of positive and negative charges in an ionic compound must equal zero.
Compounds are generally categorized into two main types for naming purposes:
Ionic Compounds: Formed between a metal and a nonmetal, or involving polyatomic ions.
Type I Ionic Compounds (Fixed-Charge Metals): Consist of a cation from a metal that forms only one type of ion (e.g., Group 1, Group 2, Aluminum, Zinc, Silver) and an anion.
Name the cation first, using the element name.
Name the anion second, by taking the root of the nonmetal element name and adding the suffix "-ide".
Example: NaCl is sodium chloride; MgBr_2 is magnesium bromide.
Type II Ionic Compounds (Variable-Charge Metals): Consist of a cation from a metal that can form more than one type of ion (typically transition metals) and an anion.
Name the cation first, using the element name followed by a Roman numeral in parentheses to indicate its charge.
Name the anion second, using the "-ide" suffix for monatomic anions.
Example: FeCl2 is iron(II) chloride; FeCl3 is iron(III) chloride.
Ionic Compounds with Polyatomic Ions: Involve polyatomic ions (groups of atoms with an overall charge).
Name the cation (element name or polyatomic ion name).
Name the anion (polyatomic ion name or monatomic anion with "-ide" suffix).
Common polyatomic ions include: NO3^- (nitrate), SO4^{2-} (sulfate), PO4^{3-} (phosphate), OH^- (hydroxide), CO3^{2-} (carbonate), NH_4^+ (ammonium).
Example: NaNO3 is sodium nitrate; (NH4)2SO4 is ammonium sulfate.
Covalent/Molecular Compounds: Formed between two nonmetals.
Use prefixes to indicate the number of atoms of each element.
The first element is named as is.
The second element takes an "-ide" suffix with a prefix.
The prefix "mono-" is generally omitted for the first element.
Prefixes: mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8), nona- (9), deca- (10).
Example: CO is carbon monoxide; CO2 is carbon dioxide; P2O_5 is diphosphorus pentoxide.
Acids: Compounds that produce H^+ ions when dissolved in water.
Binary Acids: Composed of hydrogen and one other nonmetal.
Named as "hydro-" + nonmetal root + "-ic acid".
Example: HCl (g) is hydrogen chloride, but HCl (aq) is hydrochloric acid.
Oxyacids: Composed of hydrogen, oxygen, and one other nonmetal.
If the polyatomic ion name ends in "-ate", the acid name ends in "-ic acid".
If the polyatomic ion name ends in "-ite", the acid name ends in "-ous