Materials Science: Properties and Types

Materials Science and Engineering

• Materials are classified into metals, alloys, polymers, ceramics, glasses, and composites.
• Metals have valence electrons that detach from atoms and spread in an "electron sea", making them strong, conductive, and shiny.
• Examples of metals include aluminum, steel, brass, and gold.

Bonding in Materials

• Metals bond through metallic bonding, where electrons are detached from atoms and shared among ions.
• Semiconductors bond through covalent bonding, where electrons are shared between atoms, and their electrical properties depend on minute impurities.
• Examples of semiconductors include silicon, germanium, and gallium arsenide.
• Ceramics bond through ionic bonding, where atoms behave like ions and are bound by Coulomb forces.
• Examples of ceramics include glass, porcelain, and many minerals.
• Polymers bond through covalent and weak van der Waals forces, making them lightweight and decomposable at moderate temperatures.
• Examples of polymers include plastics, nylon, Teflon, polyester, and rubber.

Classification of Materials

• Materials can be classified by structure, properties, or use.
• One way to classify materials is by the way atoms are bound together: crystalline, amorphous, type of bonding, molecular and crystal structure, and physical and mechanical properties.

History of Materials Science

• The development of civilization is associated with the discovery and use of new materials, such as stone, copper, bronze, iron, and steel.
• The discovery of quantum mechanics in the 1930s enabled an understanding of the atomic structure of materials and the development of materials science.
• Materials science combines physics, chemistry, and engineering to design and develop materials for specific applications.

Properties of Materials

• Materials respond to the environment through their mechanical, electrical, magnetic, thermal, optical, and chemical properties.
• Properties are determined by the arrangement of atoms at the atomic and microscopic levels.
• Processing of materials involves applying heat, mechanical forces, and other techniques to affect their microstructure and properties.

Importance of Materials Science

• Materials science is essential for advancing technologies, such as engine efficiency, nuclear energy, hypersonic flight, optical communications, and civil construction.
• Understanding materials is critical for all engineering disciplines, including metals, non-metals, and metalloids.

Atomic Structure and Bonding

• The periodic table classifies elements into metals, non-metals, and metalloids based on their outermost electron shell.
• Metals have partially filled outer shells, non-metals have fully filled outer shells, and metalloids exhibit properties of both metals and non-metals.
• Ionic bonding involves the transfer of electrons between atoms, resulting in a Coulomb attraction between positive and negative ions.
• Covalent bonding involves the sharing of electrons between atoms to form a bond, resulting in a directional bond.