1. Section 6.4 “Metallic Bonding”
Pre-AP Chemistry

2. Chapter 6 Objectives Section 4 Metallic Bonding
Describe the electron-sea model of metallic bonding, and explain why metals are good electrical conductors.
Explain why metal surfaces are shiny.
Explain why metals are malleable and ductile but ionic-crystalline compound are not.

3. Sec 6.4 Vocabulary
metallic bonding
malleability
ductility

4. Properties of Substances with Metallic, Ionic, and Covalent Bonds
Chapter 6
Section 4 Metallic Bonding
Properties of Substances with Metallic, Ionic, and Covalent Bonds

5. Metallic Bonds are… How metal atoms are held together in the solid.
Metals hold on to their valence electrons very weakly.
Think of them as positive ions (cations) floating in a sea of electrons

6. Sea of Electrons + Electrons are free to move through the solid.
Metals conduct electricity. +

7. Chapter 6 Section 4 Metallic Bonding Metallic Bonding
Chemical bonding is different in metals than it is in ionic, molecular, or covalent-network compounds.
The unique characteristics of metallic bonding gives metals their characteristic properties, listed below.
electrical conductivity
thermal conductivity
malleability
ductility
shiny appearance (luster)

8. Why metals are Shiny
metals are strong absorbers and reflectors of light
absorption of light excites metals electrons to higher energy levels
electrons immediately fall emitting energy at same frequency as absorbed (reflection of light)

9. Chapter 6
Section 4 Metallic Bonding
Metallic Bonding, continued
Malleability is the ability of a substance to be hammered or beaten into thin sheets.
Ductility is the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire.

10. Metals are Malleable
Hammered into shape (bend).
Also ductile - drawn into wires.
Both malleability and ductility explained in terms of the mobility of the valence electrons (sea of electrons)

11. Due to the mobility of the valence electrons, metals have:
Notice that the ionic crystal breaks due to ion repulsion!
1) Ductility
2) Malleability
and

12. Malleable +
Force

13. Malleable + + + + Force + + + + + + + +
Mobile electrons allow atoms to slide by, sort of like ball bearings in oil. + + + +
Force + + + + + + + +

14. Metallic properties..
The valence electrons of metal atoms can be modeled as a sea of electrons.
metals are..
a) good conductors of electric current
b) ductile and malleable which explains the mobility of valence e-

15. Ionic solids are brittle
Force + -

16. Ionic solids are brittle
Strong Repulsion breaks a crystal apart, due to similar ions being next to each other. + -
Force + - + - + -

17. Chapter 6 Section 4 Metallic Bonding The Metallic-Bond Model
In a metal, the vacant orbitals in the atoms’ outer energy levels overlap.
This overlapping of orbitals allows the outer electrons of the atoms to roam freely throughout the entire metal.
The electrons are delocalized, which means that they do not belong to any one atom but move freely about the metal’s network of empty atomic orbitals.
These mobile electrons form a sea of electrons around the metal atoms, which are packed together in a crystal lattice.

18. Chapter 6 The Metallic-Bond Model, continued
Section 4 Metallic Bonding
The Metallic-Bond Model, continued
The chemical bonding that results from the attraction
between metal atoms and the surrounding sea of
electrons is called metallic bonding.

20. Chapter 6 Objectives Section 4 Metallic Bonding
Describe the electron-sea model of metallic bonding, and explain why metals are good electrical conductors.
Explain why metal surfaces are shiny.
Explain why metals are malleable and ductile but ionic-crystalline compound are not.

21. End of Sec 6.4