Materials and their Properties

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Materials and their Properties

• Chapter 11

Great Idea A materials properties result from
its constituent atoms and the arrangements of
chemical bonds that hold those atoms together
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Chapter Outline

• Materials and the Modern World
• The Strengths of Materials
• Electrical Properties of Materials
• Magnetic Properties of Materials
• Microchips and the Information Revolution

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Materials and the Modern World
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Materials and the Modern World

• Materials define technical sophistication
• Chemists contributions
• Properties of Materials
• The kind of atoms of which it is made
• Arrangement of atoms
• Type of bonding of atoms

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The Strengths of Materials
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Different Kinds of Strength

• Strength
• Compressive
• Tensile
• Shear
• Elastic Limit
• Strength depends on type and arrangement of bonds

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Composite Materials

• Composite materials
• Combination of materials
• Increase strength

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Electrical Properties of Materials
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Conductors Insulators

• Conductors
• Electrical conductor
• Electrons flow freely
• Electrical resistance
• Draining of energy from current
• Insulators
• No electricity flows through them

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Semiconductors

• Semiconductors
• Neither good conductors or insulators
• Example Silicon
• Conduction electrons
• Hole

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Superconductors

• Superconductivity
• Absence of electrical resistance
• At cold temperature electrons move without losing
  energy
• How?
• Electron-ion interactions

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Magnetic Properties of Materials
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Magnetic Properties of Materials

• Magnetic field
• Due to electrical current
• Electrons spinning
• Arrangement of atomic magnets
• Determines level of magnetism

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Microchips and the Information Revolution

• New materials often lead to new technologies that
  change society

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Doped Semiconductors

• Doping
• Addition of minor impurity
• N-type semiconductor
• Extra electron
• P-type semiconductor
• Hole

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Diodes

• Diode
• Combination of p- and n-type semiconductors
• One-way gate

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The Transistor

• Transistor
• Control flow of electrons
• Emitter
• Base
• Collector
• Uses
• Cell phone
• Computer

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Microchips

• Microchip
• Complex array of p- and n-type semiconductors
• Integrated circuit
• Design
• Layers interconnected

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Information

• The binary digit or bit
• Two possible answers to a simple question
• 8 bits 1 byte

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Computers

• Computer
• Stores and manipulates information
• Central Processing Unit (CPU)
• Nanotechnology