1. Bellringer 3-17 What property makes metals good electrical conductors?
The electron mobility accounts for the high electrical conductivity of metals.
What happens when a metal is subjected to pressure?
The sea of drifting valence electrons insulates the metal cations from each other and the metal cations slide past one another. This explains the malleability of metals.

2. Metallic Bonds Metals are composed of closely packed Cations.
Metallic Bonds consist of the attraction of the free-floating valence electrons for the positively charged metal ions

3. Metallic Bonds
Metal atom’s valence electrons are modeled as a “sea” of electrons.
These electrons are shared by all of the nuclei in a metallic solid.

4. Metallic Bonds Alloys-
Mixtures composed of two or more elements of which one is a metal.
Alloys are useful because they are often superior to their component elements.
Harder, more durable, easier to cast, resistance to corrosion
Brass- copper &
zinc alloy
Sterling Silver
Silver & brass
alloy

5. Practice Problems
pg207 # 43, 44, 46, 47, 48, 49, 50, 51.

6. COVALENT BONDS Covalent Bond Atoms held together by SHARING electrons
Molecule
A neutral group of atoms joined together by covalent bonds
Diatomic molecule
A molecule consisting of two atoms
Molecular compound
A compound composed of molecules

7. Molecular Compounds

8. Ionic compound VS. Molecular compounds
The ions of the sodium ion are separate and arrayed in a regular pattern
The two hydrogen atoms and one oxygen atom are bonded together in one molecule.
Most molecular compounds are gases or liquids at room temperature and have lower melting points than ionic compounds.

9. Molecular Compounds Water H2O Oxygen O2 Ethane C2H6 Carbon Dioxide CO2
Carbon Monoxide CO

10. Bond Dissociation Energies
The energy needed to break a covalent bond.
Expressed as energy needed to break one mole (mol) of bonds
= 6.02 X bonds
Larger Dissociation Energy= stronger covalent bond = more stable!