Podcast
Questions and Answers
What is a characteristic property of crystalline materials?
What is a characteristic property of crystalline materials?
- Brittleness
- Amorphous structure
- Long-range atomic order (correct)
- Optical transparency
What type of bonding is described as temporary and fluctuating with time?
What type of bonding is described as temporary and fluctuating with time?
- Metallic bonding
- Van der Waals bonding (correct)
- Ionic bonding
- Covalent bonding
Which type of materials lack a crystalline structure?
Which type of materials lack a crystalline structure?
- Polycrystalline materials
- Metallic materials
- Non-crystalline materials
- Amorphous materials (correct)
Which term describes molecules that have a permanent dipole moment?
Which term describes molecules that have a permanent dipole moment?
What model illustrates atoms as spheres touching each other at their closest points?
What model illustrates atoms as spheres touching each other at their closest points?
On a bonding tetrahedron, what is located at each vertex to represent the four bonding types?
On a bonding tetrahedron, what is located at each vertex to represent the four bonding types?
Which crystal structure has atoms located at each of the cube's corners and center of its faces?
Which crystal structure has atoms located at each of the cube's corners and center of its faces?
What term is used for atomic bonds that are mixtures of two or more extreme types of bonds?
What term is used for atomic bonds that are mixtures of two or more extreme types of bonds?
What is the term used to represent small repeat entities in crystal structures?
What is the term used to represent small repeat entities in crystal structures?
What is the coordination number for face-centered cubic crystal structures?
What is the coordination number for face-centered cubic crystal structures?
Which material class is associated with metallic bonding?
Which material class is associated with metallic bonding?
What type of bonding is found in molecular solids?
What type of bonding is found in molecular solids?
Flashcards are hidden until you start studying
Study Notes
Crystal Structure and Properties
- Crystal structure affects material properties, such as brittleness (e.g., magnesium and beryllium) vs. ductility (e.g., gold and silver)
- Noncrystalline materials (e.g., ceramics and polymers) are often optically transparent, whereas crystalline forms are opaque or translucent
Crystalline and Non-Crystalline Materials
- Crystalline materials have long-range atomic order, with atoms arranged in a repetitive three-dimensional pattern
- Non-crystalline materials lack long-range atomic order and exhibit no crystalline structure
Polycrystalline Materials
- Exhibit long-range order due to the formation of multiple small crystalline regions or grains, each with its own crystallographic orientation
Atomic Hard-Sphere Model
- Represents atoms as spheres that touch each other at their closest points, illustrating nearest-neighbor interactions
Lattice and Unit Cells
- Lattice refers to a three-dimensional array of points coinciding with atom positions (or sphere centers)
- Unit cells are small repeat entities that make up the crystal structure, often subdivided for convenience
Face-Centered Cubic (FCC) Crystal Structure
- Common crystal structure found in many metals, characterized by a cubic unit cell with atoms at corners and face centers
- Important characteristics include coordination number and atomic packing factor (APF)
Bonding Types
- Ionic, covalent, metallic, and van der Waals bonding types exist, and many real materials exhibit mixed bonding
- Bonding tetrahedron represents these bonding types, with mixed-bond types on the edges
- Correlations exist between bonding type and material class (e.g., polymers: covalent, metals: metallic, ceramics: ionic/mixed ionic-covalent)
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
