Chapter 5.3 Names and Formulas of Ionic Compounds
Objectives Name cations, anions, and ionic compounds Write chemical formulas for ionic compounds such that an overall neutral charge is maintained. Explain how polyatomic ions and their salts are named and how their formulas relate to their names.
Chemical names and Formulas Calcium carbonate – Sodium chloride – Dihydrogen monoxide – These are their chemical and common names Chemical names help to describe the atomic makeup of the compounds
Chemical formula for ionic compound Ionic compound consists of lattice of positive and negative ions held together by mutual attraction. Chemical formula represented by one unit cell Simplest ratio of the compounds positive and negative ions Aluminum sulfate below consists of aluminum cations and sulfate ions Al2(SO4)3 Subscript 3 refers to everything inside the parentheses giving 3 sulfate ions, with a total of 3 sulfur atoms and 12 oxygen atoms Subscript 2 refers to 2 Aluminum atoms Subscript 4 refers to 4 oxygen atoms in the sulfate ion Note: when you only have one of an atom, no subscript is used Note: parentheses are used to identify polyatomic ion as one unit
Monatomic ions Ions formed from a single atom Examples Na+1 lose one electron Mg2+ S2- gain two electrons N-3 Cl1-
Naming Compounds with Polyatomic Ions Same as naming for ionic compounds except Name polyatomic ion as one unit Example: AgNO3 Use parentheses if more than one polyatomic ion Example Al2(SO4)3 silver nitrate Show 2 Al+3 ions and 3 SO4-2 ions aluminum sulfate
Writing Formulas and Naming Compounds with Polyatomic Ions Write the formula for these: tin(IV) sulfate calcium chloride lithium nitrate calcium nitrite potassium perchlorate Sn(SO4)2 CaCl2 LiNO3 Ca(NO2)2 KClO4