![Page 1: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/1.jpg)
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
Structure and Properties of SOLIDS
![Page 2: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/2.jpg)
Ionic Crystals• crystal lattice• electrostatic attraction
b/w ions of opposite charge (ionic bonding)
• ions held in fixed position
• 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
![Page 3: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/3.jpg)
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)
![Page 4: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/4.jpg)
Molecular Crystals
• Neutral (nonpolar) molecules held together by weak intermolecular forces (LDF)
• Low melting pt • Soft• Non- conductive• Solubility in water?
![Page 5: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/5.jpg)
Why does ice float?• When water molecules
freeze, they form a hexagonal crystal of H2O molecules linked by H bonds.
![Page 6: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/6.jpg)
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
![Page 7: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/7.jpg)
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?
![Page 8: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/8.jpg)
Summary
![Page 9: Solids differ: Hardness Melting point Flexibility Conductivity](https://reader035.vdocument.in/reader035/viewer/2022062410/568163a1550346895dd4a13b/html5/thumbnails/9.jpg)
Homework
Pg. 254 #: 1-4,6-9
Self Quiz Pg. 261Chapter Review Pg. 262