Period 6 Group 6

I.Common Polyatomic Ions II.Naming Compounds with Polyatomic Ions III.Naming Acids Based on its Anions IV.Common Acids V.Writing Formulas/Names with Given Information

Polyatomic ion: An ion consisting of two or more atoms bound together (a binary compound only consists of two elements) Example/Question 1: What is special about the polyatomic ions such as hydroxide, peroxide, and cyanide compared to the other common polyatomic ions? Answer: They are the only ones with an –ide ending.

 Oxyanion: A polyatomic ion containing at least one oxygen atom & one or more atoms of at least one other element.  Common polyatomic ions must be memorized.  Use the suffix –ite (smaller # of oxygen atoms) or –ate (larger # of oxygen atoms) when there are two members in an oxyanion series.  Use the prefixes hypo- (less than) and per- (more than) when more than two oxyanions make up a series.

 To name compounds with polyatomic ions, polyatomic ions must be recognized by its composition and charge.  When a metal is present that forms more than one cation, a Roman numeral is required.  Parentheses are used to enclose the ion and a subscript is written after the closing parenthesis.  Example/Question 2: What must we add to specify the cation charge of the metal in ionic compounds containing polyatomic ions? ◦ Answer: We must add a Roman numeral.

Example/Question 3: If the anion name ends in –ite, what is the suffix used in the acid name? Answer: The suffix used in the acid name would be –ic. Example/Question 4: What are the rules to naming acids based on its anion composition? Answer: The rules to naming acids if the anion doesn’t contain oxygen, is the acid is named with the prefix hydro- and the suffix – ic. When the anion contains oxygen, the acid name is formed from the root name of the central element of the anion or the anion name with a suffix of –ic or –ous. Use –ic when the anion name ends in –ate or use –ite when the anion name ends in –ite. *Refer to the orange box on the left for more information.

 Acid: A substance that produces hydrogen ions (H+) in solution; a proton donor.

Acids That Do Not Contain Oxygen  HF – hydrofluoric acid  HCl – hydrochloric acid  HBr – hydrobromic acid  HI – hydroiodic acid  HCN – hydrocyanic acid  H 2 S – hydrosulfuric acid Note: All of the names of acids that don’t have oxygen have the prefix hydro-

Acids That Do Contain Oxygen  HNO 3 – nitric acid  HNO 2 – nitrous acid  H 2 SO 4 – sulfuric acid  H 2 SO 3 – sulfurous acid  H 3 PO 4 – phosphorus acid  HC 2 H 3 O 2 – acetic acid *Common acids must be memorized.

 Learn the following: (for each of the common polyatomic ions) ◦ name ◦ composition ◦ charge  These all must be learned in order to write the formula for a given name or to write the name for a given formula.

 Example/Question 5- Write the formula for iodine dihydrogen phosphate.  Given info: name  Iodine = I-  Dihydrogen phosphate = H 2 PO 4 - ◦ I- + H 2 PO 4 -  = IH 2 PO 4

 1. What is the difference between a binary compound and an ionic compound containing polyatomic ions?  2. What do we add when more than one polyatomic ion appears in a chemical formula?  3. What is the prefix & suffix attached to the root name for the element, if the anion doesn’t contain oxygen?  4. What do the acids names that do not contain oxygen all have in common?  5. What is the name for Ti(NO3)3?

 1. An ionic compound containing polyatomic ions contains more than 2 elements.  2. We add parentheses to enclose the ion and a subscript after the closing parenthesis.  3. The prefix is hydro- and the suffix is –ic.  4. They all have the prefix hydro-.  5. The name is titanium nitrate.

 ICAL_FORMULAS_POLYATOMIC_IONS.jpg ICAL_FORMULAS_POLYATOMIC_IONS.jpg  nomenclature/images/polyions.jpg nomenclature/images/polyions.jpg   1FA43CF9A342/0/ChemistryNamingCompounds3.pdf 1FA43CF9A342/0/ChemistryNamingCompounds3.pdf  ook/index.jsp ook/index.jsp   Microsoft PowerPoint Clip Art