U.5 AND 6 SOLID STATE Flashcards
Metallic solids are a crystalline network formed by an…
ordered network of positive ions inmerse in an e- sea made of valence e-.
Properties of metallic solids?
- Soft or hard
- MP variates very low or high
- High thermal and electrical conductivities
- Malleable and ductile
What are the 2 types of crystal structure?
- CLOSED-PACKED STRUCTURES
- UNIT CELLS
What are the 2 tipes of closed-packed structures?
- HEXAGONAL CLOSE-PACKED (2 layers)
- CUBIC CLOSE-PACKED (3 layers)
What are the types of unit cells?
- CUBIC (a=b=c, all 90º)
- TETRGONAL (a=b!=c, all 90º)
- ORTHORHOMBIC (a!=b!=c, all 90º)
- MONOCLINIC (a!=b!=c, 2 angles 90º)
- HEXAGONAL (a=b!=c, 2 angles 90º, an other 120º)
- RHOMBOHEDRAL (a=b=c, all different from 90º but the same)
- TRICLINIC (a!=b!=c, all different from 90º and from each other)
Types of unit cells depending on the possition of the atoms?
- Simple cubic
- Body-centered cubic
- Face-centered cubic
How to calculate the number of atoms inside?
ni + 1/2 nf + X.nc
What is X in the formula to calculate the number of atoms inside?
Hexagonal close-packed - 1/8
Cubic closed-packed - 1/6
What is the coordination number(CN)?
Numer of atoms that are connected to the central atom.
What is CN for a simple cubic?
6
What is CN for a body-centered cubic?
8
What is CN for a face centered cubic?
12
What is CN for a hexagonal close-packed?
12
The electron sea model accounts for the….
electrical conductivity of metals and the easiness of deformation of metals.
The band theory is based on the..
MO theory
