1. Section 4 – pg 198 Bonding in Metals
Chapter 5
Section 4 – pg 198
Bonding in Metals

2. Pg 199
Metals and Alloys
Alloy: a mixture made of two or more elements, at least one of which is a metal
Alloys are generally stronger and less reactive than the pure metals from which they are made
Zinc + Copper = Brass Carbon + Iron = Steel
Copper + Silver = Sterling Silver

3. Physical Properties of Alloys
Pg 199
Physical Properties of Alloys
The properties of an alloy can differ greatly from those of its individual elements
May also retain many physical properties of the metals depending on how they are mixed

4. Chemical Properties of Alloys
Pg 199
Chemical Properties of Alloys
The chemical properties of an alloy are different than what it is made of
IE: Iron is strong and a good material to make tools out of but it rusts so we add carbon to get steel, which is hard and does not rust
Iron rusts
 Steel does not

5. Pg 200
Metallic Bonding
The properties of solid metals and their alloys can be explained by the structure of metal atoms and the bonding between those atoms
Most metals have 1-3 valence electrons
These are held loosely and are easily lost causing the metal atom to become positively charged

6. Metallic Bonding Continued
Pg 200
Metallic Bonding Continued
Metal atoms combine in regular patterns in which the valence electrons are free to move from atom to atom
Crystalline Solids
Positively charged ions are closely packed together
Metallic Bond: an attraction between a positive metal ion and the many electrons surrounding it

7. Pg 201
Metallic Properties
The “sea of electrons” model of metallic bonding helps explain the malleability, ductility, luster. High electrical conductivity, and high thermal conductivity of solid metals

8. Malleability and Ductility
Pg 201
Malleability and Ductility
Metals are malleable (can be rolled into sheets or beaten into shapes) and ductile (easily bent and pulled into thin strand or wire) because the positive ions are attracted to the loose electrons all around them rather than to the other metal ions
This is also why metals bend before breaking

9. Luster A metals luster (shininess) is due to its valence electrons
Pg 202
Luster
A metals luster (shininess) is due to its valence electrons
When light strikes these electrons, they absorb the light and then give it off again

10. Electrical Conductivity
Pg 202
Electrical Conductivity
Metals conduct current easily b/c the electrons in a metal can move freely among the atoms

11. Pg 202
Thermal Conductivity
Metals conduct heat easily because of the valence electrons’ freedom of motion within a metal or metal alloy

12. Chapter 5 Section 4 Homework – pg 203

13. 1A. What is an alloy?

14. 1B. From what pure metals is stainless steel made?

15. 1C. Compare and contrast the general properties of alloys and pure metals

16. 2A. What is a metallic bond?

17. 2B. Explain how metal atoms form metallic bonds
2B. Explain how metal atoms form metallic bonds. What role do the valence electrons play?

18. 2C. Review what you learned earlier about ionic bonds
2C. Review what you learned earlier about ionic bonds. How does a metallic bond differ from an ionic bond?

19. 3A. Name 4 properties of metals. What accounts for these properties?

20. 3B. In a light bulb, a thin tungsten wire filament that is wound in a coil conducts electric current. Describe two properties of the metal tungsten that make it good material for the filament

21. 3C. Why is it safer to use a nonmetal mixing spoon when cooking something on a stove?