Untitled Quiz

Historical Perspective

• Materials are fundamental to our culture, influencing daily life (transportation, housing, communication).
• Society advancements are linked to material manipulation skills.
• Civilizations were categorized by material development (Stone Age, Bronze Age, Iron Age).
• Early humans used natural materials (stone, wood, clay, skins).
• Techniques to create materials with superior properties were discovered (pottery, metals).
• Heat treatments and additions of substances altered material properties.
• Understanding the relationships between material structure and properties advanced in recent centuries.
• Thousands of materials exist with specialized characteristics, meeting contemporary needs.
• Technological progress often follows advancements in material understanding. (e.g., automobiles & steel, semiconductors)

Materials Science and Engineering

• Materials science investigates relationships between material structure and properties.
• Materials engineering designs materials to achieve specific properties.
• Materials scientists develop/synthesize new materials.
• Materials engineers use existing materials to create products/systems.
• Material structure relates to internal component arrangement (subatomic, atomic, microscopic, macroscopic).
• Material properties are responses to external stimuli (e.g., deformation to force, response to light).
• Properties are categorized as mechanical, electrical, thermal, magnetic, optical, and deteriorative.
• Material performance is a function of processing, structure, and properties.

Why Study Materials Science and Engineering?

• Design problems frequently involve materials selection.
• Materials selection decisions rely on service conditions, material deterioration, and economics, or material cost.
• A material's ideal combination of properties will rarely exist in all instances.
• Compromises between different material properties may be necessary.
• Material deterioration during service (temperature, environment) must be factored into selections.

Classification of Materials

• Primary material categories include metals, ceramics and polymers.
• Composites are engineered combinations of materials.
• Metals: Composed of metallic elements or alloys (often with non-metallic elements) with an ordered arrangement on atoms. High density.
• Ceramics: Compounds of metallic and non-metallic elements. Stiff and strong, brittle, resistant to high temperatures. Good insulators.
• Polymers: Large molecular structures (often in a chain-like manner), typically carbon based. Flexible, relatively low density.
• Advanced materials: Include semiconductors, biomaterials, smart/nano materials, used in high-tech applications.

Atomic Structure and Interatomic Bonding

• Solid material properties depend on atomic arrangements and interactions.
• Atoms consist of a nucleus (protons, neutrons) surrounded by electrons.
• Atomic number (Z) = number of protons.
• Atomic mass (A) = number of protons + neutrons.
• Atomic weight is the average of isotopes' atomic masses.
• Electrons exist in quantized energy levels (orbitals).
• Quantum numbers describe electrons (n, l, ml, ms).
• Pauli Exclusion Principle states no more than 2 electrons per energy state, with opposite spins.
• Electron configurations fill orbitals from lowest energy to highest.
• Outermost shell electrons are valence electrons.
• Valence electrons determine chemical bonding characteristics.

Primary Interatomic Bonds

• Ionic bonding: Transfer of electrons, creating ions that attract.
• Covalent bonding: Sharing of electrons between atoms.
• Metallic bonding: Valence electrons are delocalized in a "sea", holding positive ions together.

Secondary Interatomic Bonds

• Van der Waals bonding: Weak forces between atoms/molecules, often temporary dipoles.
• Hydrogen bonding: Strong dipole-dipole bonds, involving hydrogen atoms.

Molecules

• Molecules are groups of atoms covalently bonded together.
• Molecular properties often depend on secondary (intermolecular) bonds.
• Substances in either solid, liquid, or gaseous states exist by intermolecular forces.