2. Ionic Compounds, Cont. Using The Stock System

3. Chemistry Joke A neutron sits down at the counter and asks the waitress, “How much for a coke?” The waitress replies… “For you, no charge!”

4. Elements We’ve Been Avoiding… Metals that form more than one ion. Metals that form more than one ion. These include ALL metals not in Groups 1A or 2A except Ag, Zn,Cd, and Al. These include ALL metals not in Groups 1A or 2A except Ag, Zn,Cd, and Al. Ag Ag +1 ; Zn Zn +2 ; Cd Cd +2 Ag Ag +1 ; Zn Zn +2 ; Cd Cd +2 Formulas are written using the same 3-step Criss Cross method. Formulas are written using the same 3-step Criss Cross method. The difference comes in how they are named. The difference comes in how they are named.

5. For Example… Iron forms both a 2+ ion and a 3+ ion. If we just name the ionic compound that iron forms with chlorine, iron chloride, is it iron +2 or iron +3? Iron  2+ or 3+ Would the formula be FeCl 2 or FeCl 3 ? So…to name compounds with these metals, we use the Stock Naming System. This system uses Roman numerals to indicate charge. (I), (II), (III), (IV), (V)

6. Using the Stock System Chromium can form ions of +3 and +2. The Stock System uses Roman numerals to indicate charge, so we name the ion Chromium (III) or Chromium (II). These Roman numerals will always refer to the charge of the metal before them. So…Chromium (III) is Cr 3+ And…Chromium (II) is Cr 2+ What is the ion symbol for Tin (IV)? Sn 4+

7. Using the Stock System What is the name of CuCl 2 ? Now we need to ask, “Do we need the stock system? Does the compound begin with a metal that is NOT Al, Cd, Zn, Ag or in Group 1A, 2A? So…you have to find the charge on the metal in order to name it—the metal ion needs a Roman numeral! Yes!

8. Let’s Name CuCl 2 and SnO 2 Copper (II) Chloride and Tin (IV) Oxide

9. Practice Copper (III) Chloride Zinc Oxide Silver Nitride Iron (III) Oxide CuCl 3 ZnO Ag 3 N Fe 2 O 3

10. Go the other way… Cu 2 O 3 FeO AgCl Sn 3 N 4 Copper (III) Oxide Iron (II) Oxide Silver Chloride Tin (IV) Nitride

11. Chemistry Joke Q: What does a surprised chemist say? A: O Mg!