Structure & Properties of Solids

Understanding the structural and bonding characteristics of substances in the solid phase – “materials science”

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Composite MaterialsA material composed of two or more distinct materials that remain separate from each other in the solid phase

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Four types of solid structures we will explore:1. Ionic Crystals2. Metallic Crystals3. Molecular Crystals4. Covalent Network Crystals

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Ionic Crystals

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Form when metal reacts with non-metal

Composed of oppositely charged ions; electrostatically attracted to each other

Metallic Crystals

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Metal atoms onlyBound by a “sea of electrons”;

creating overall region of negative charge explains metallic properties

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Molecular Crystals

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Composed of individual molecules held together by intermolecular forces

Properties vary depending on intermolecular forces present

Covalent Network Crystals

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Atoms form covalent bonds in an inter-woven network

Properties:HardnessNon-conductorHigh melting

point

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When heated beyond it’s MP, then cooled quickly, SiO2 changes from a) “sand” to b) “glass”

SiO2 glass can be strengthened by adding B2O3, used in lab and kitchen glassware (Pyrex)

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SemiconductorsClick icon to add pictureType of covalent network solid (containing Si or Ge atoms)A substance that conducts a slight electric current at room temperatureA slight increase in temperature causes a significant increase in conductivity

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www.youtube.com/watch?v=u3GdpbKTPQQ

Future of Materials Science 3D Printing

CNN: http://www.youtube.com/watch?v=e0rYO5YI7kA

Deeper explanation: http://www.youtube.com/watch?v=X5AZzOw7FwA

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