Ionic Compounds, Cont.Ionic Compounds, Cont.

UsingThe Stock System

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!”

Elements We’ve Been Avoiding…Elements We’ve Been Avoiding…

• Metals that form more than one ion.Metals that form more than one ion.• These include These include ALLALL metals not in Groups 1A or 2A metals not in Groups 1A or 2A

exceptexcept Ag, Zn,Cd, and Al.Ag, Zn,Cd, and Al.• Ag Ag AgAg+1+1; Zn ; Zn Zn Zn+2+2; Cd; Cd Cd Cd+2+2

• Formulas are written using the same 3-step Criss Formulas are written using the same 3-step Criss Cross method.Cross method.

• The difference comes in how they are named.The difference comes in how they are named.

For Example…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 FeCl2 or FeCl3?

• 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)

Using the Stock SystemUsing 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 Cr3+

• And…Chromium (II) is Cr2+

• What is the ion symbol for Tin (IV)? SnSn4+4+

Using the Stock SystemUsing the Stock System• What is the name of CuCl2? • 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!Yes!

Let’s Name CuClLet’s Name CuCl22 and SnO and SnO22

Copper (II) Chloride and Tin (IV) OxideCopper (II) Chloride and Tin (IV) Oxide

PracticePractice• Copper (III) Chloride

• Zinc Oxide

• Silver Nitride

• Iron (III) Oxide

CuClCuCl33

ZnOZnO

AgAg33NN

FeFe22OO33

Go the other way…Go the other way…• Cu2O3

• FeO

• AgCl

• Sn3N4

Copper (III) OxideCopper (III) Oxide

Iron (II) OxideIron (II) Oxide

Silver ChlorideSilver Chloride

Tin (IV) NitrideTin (IV) Nitride

Chemistry Joke

Q: What does a surprised chemist say?

A: O Mg!