Notes #12

Review  To find the number of valence electrons in an atom of a representative element, simply look at its group number.

Why do atoms form ions?  To fulfill octet rule.  To be stable and happy like a noble gas.  They gain and lose electrons to have a COMPLETE outer shell.  But where do these electrons come from?

OTHER ELEMENTS! This creates something we call:  Ionic Compounds:  Compounds that are formed by elements transferring their electrons to each other.  Ionic Bonds:  The electrostatic forces that hold ions together in ionic compounds.

Ionic Compounds: Properties  Are electrically neutral (no charge!)  Most ionic compounds are crystalline solids at room temperature.

Ionic Compounds: Properties  Ionic compounds generally have high melting points.  Ionic compounds can conduct an electric current when melted or dissolved in water.

How Ionic Compounds are made:

Naming. Easy Peasy.  Write the actual name of the cation.  Then, write the name of the anion with the end ending in –ide.  Ex: Nitrogen  Nitride; Oxygen  Oxide; etc  Cations always first, Anions always last

Practice Cation always First. Anion Always Last. Must be neutral… Criss-Cross Rule

Polyatomic Ions

Find these on your handout:

Ionic Compounds with polyatomic ions:  Write the chemical formula and name it:  Magnesium and nitrate  Lithium and sulfate  Potassium and cyanide

Transition Metals (Groups 1B to 8B)  They always form CATIONS.  Therefore, they will have a positive charge.  The charges of the cations of many transition metal ions must be determined from the number of electrons lost.  Transition metals can form more than one ion. (Exceptions: Ag +, Cd +2, and Zn +2 )

Symbols and Names of Common Transition Metal Ions SymbolStock NameClassical Name Cu + Copper (I) ionCuprous ion Cu +2 Copper (II) ionCupric ion Fe +2 Iron (II) ionFerrous ion Fe +3 Iron (III) ionFerric ion Co +2 Cobalt (II) ionCobaltous ion Co +3 Cobalt (III) ionCobaltic ion

Practice  Cobalt (III) fluoride  Copper (II) chloride  Fe 2 O 3  CuF

Lab Activity  Cut and Paste Ionic Compounds!