Unit 2: Chemical Nomenclature Section 2: Polyatomic & Stock System Ions

Polyatomic Ions A group of two or more elements that stay together and act as one ion Example: NH4+ Nitrogen and Hydrogen are one ion

Common Polyatomic Ions NH4+  Ammonium NO2-  Nitrite NO3-  Nitrate SO32-  Sulfite SO42-  Sulfate OH-  Hydroxide PO33-  Phosphite PO43-  Phosphate CO32-  Carbonate

Naming Polyatomic Ions General way binary compounds are named Use the name of the polyatomic ion In most cases, parentheses are needed around polyatomic ions

Examples of Polyatomic Compounds Sodium and Nitrate Formula: Na+ and NO3-  NaNO3 Because there are 1+ and 1-, nothing else needs to be done Name: Sodium Nitrate

Examples of Polyatomic Compounds Calcium and Nitrate Formula: Ca2+ and NO3-  Ca(NO3)2 The parentheses shows that the entire nitrate ion gets doubled Name: Calcium Nitrate

Let’s practice!!!

Stock System Ions Ion that can have more than one charge Example: Fe2+ and Fe3+ Most transition metals are stock system ions

Naming Stock System Ions Same method as naming Polyatomic compounds Roman numerals are used to specify the charge 1  I 2  II 3  III 4  IV - 5  V

Examples of Stock System Compounds Tin and Chlorine Formula 1: Sn2+ and Cl-  SnCl2 Name 1: Tin (II) Chloride Formula 2: Sn4+ and Cl-  SnCl4 Name 2: Tin (IV) Chloride

Examples of Stock System Compounds Copper and Nitrate Formula 1: Cu+ and NO3-  CuNO3 Name 1: Copper (I) Nitrate Formula 2: Cu2+ and NO3-  Cu(NO3)2 Name 2: Copper (II) Nitrate

Let’s practice!!!