1. Metallic Compounds

2. Metallic Bonds
Metals are not ionic, but share several properties with ionic compounds
Bonds are based on the attraction of particles with unlike charges
Metals form lattices, 8-12 other metal atoms closely surround each other

3. Valence Electrons Metal atoms have at least 1 valence electrons
Don’t share or lose (with neighbors)
Crowded lattice, metal atoms outer energy level overlap
“Sea of Electrons”

4. Sea of Electrons
Proposes that all metal atoms in a metallic solid contribute their valence electrons to form a “sea” of electrons
Surrounds the metal cation in the lattice
This allows the electrons to move freely from one atom to the next
Delocalized electrons – electrons that are free to move

5. Metallic Bond
The attraction of a metallic cation for delocalized electrons

6. What are the physical properties of metallic solids?

7. Physical Properties of Metallic Solids
Melting and Boiling points
Melting points vary greatly and are moderately high
Boiling points are moderately high, but more extreme than melting points
Since cations and electrons are already mobile, this lowers the melting point

8. Physical Properties of Metallic Solids
Malleable – hammered into sheets
Ductile – drawn into wire
Mobile electrons can be pushed or pulled past each other
Durable (generally)
Mobile cations, but strongly attracted to electrons and not easily removed

9. Physical Properties of Metallic Solids
Conductivity
Electrical
Electrons move easily as part of an electrical current
Thermal
Electrons move heat from one place to another

10. Physical Properties of Metallic Solids
Hardness and Strength
As the number of delocalized electrons increases, the properties of hardness and strength also increase

11. Work with your table.
Compare and Contrast the physical properties of ionic and metallic solids.

12. Design an Experiment
You are given two unknown solids, you know one is an ionic solid and one is a metallic solid.
Create a procedure with at least two different tests to determine the identity of the unknown solids.
Tell me why that test will determine if the solid is ionic or metallic. (Explain your reasoning)

13. Alloy An alloy is a mixture of elements that has metallic properties
Divided into two categories
Substitutional alloys
Interstitial Alloys

14. Alloys Substitutional Interstitial
Some atoms in the original metallic solid are replaced by other metals of similar atomic size
Ex. Sterling Silver – silver atoms are replaced by copper atoms, properties of both
When small holes (interstices) in a metallic lattice are filled with smaller atoms
Ex. Carbon Steel – holes in the iron lattice are filled with carbon atoms, physical properties are changed, the carbon makes the iron stronger and less ductile

15. Properties of Alloys
Differ from the properties of the elements they contain
Differ in properties depending on how they are manufactured, or the heating and cooling process