Structure and Properties of SOLIDS
Solids differ:
• Hardness
• Melting point
• Flexibility
• Conductivity
Solids form crystal lattice structures:
• Repeating pattern of molecules
• Determined by x-ray crystallography
Categories of solids:
• Ionic (metals + nonmetals)
• Metallic (metals)
• Molecular (nonmetals)
• Covalent Network
– Metalliod compounds (SiC, SiO2)
– carbon compounds C (s)
• diamond, graphite
Ionic Crystals
• Hard
• Brittle
• Good electrical
conductivity as a liquid
and in aqueous solution
• High melting points
– Solid  liquid (weaken
ionic attraction, 
distance between ions)
– Held together by Ionic
forces: STRONGEST
• crystal lattice
• electrostatic attraction
b/w ions of opposite
charge (ionic bonding)
• ions held in fixed
position
Metallic Crystals
Metallic Bonding: fixed nuclei, loosely
held mobile valence e- (“e- sea” 
delocalized e-)
• Shiny/silvery: metallic e- absorb
energy from all λ
• Easily oxidized= loose e- = 
ionization energy=lose e• Flexible: Strong non-directional
bonding= electron sea
• Strength: closely packed crystal
• Electrical conductivity
• Thermal conductivity
• Soft (Pb) or hard (Cr)
•  mp (Hg) or mp (W)
Molecular Crystals
• Neutral (nonpolar)
molecules held together
by weak intermolecular
forces (LDF)
• Low melting pt
• Soft
• Non- conductive
• Solubility in water?
Why does ice float?
• When water molecules
freeze, they form a
hexagonal crystal of H2O
molecules linked by H
bonds.
Covalent Networks
• Highest melting pt
– held together by continuous directional
covalent bonds
– C-C bonds in a network are interlocked
and are stronger than the sum of
individual C-C bonds
• Hard
–
–
–
–
Stronger than ionic or molecular crystals
Diamond- large tetrahedral network
SiO2: Quartz (a) and Glass (b)
Which do you think is stronger?
• Brittle
• Insoluble
• Non-conductive: e- movement
restricted by network
Covalent Networks of CARBON
•
•
•
•
C can form 4 bonds
Many structures
Nanotechnology?
Graphite is able to
conduct electricity and
is a lubricant
– What is different about
graphite?
Summary
Homework
Pg. 254 #: 1-4,6-9
Self Quiz Pg. 261
Chapter Review Pg. 262