Chapter 12 Flashcards
What is a Crystalline Lattice (of solid)?
any arrangement of atoms in a crystalline solid.
What is a Unit Cell?
A small piece/collection of atoms, ions, molecules. Focus on Cubic unit cells!
What are the 3 types of Cubic Cells?
Simple Cubic, Body-Centered Cubic, and Face-Centered Cubic.
Simple Cubic:
1 atom on each corner: l=2r
Body-Centered Cubic:
1 atom on each corner, 1 atom in center of cube;
l=4r/sqrt3
Face-Centered Cubic:
1 atom on each corner, 1 atom on center of each cube face. l=2*sqrt2r.
Coordination Number:
The number of atoms with which each atom is in direct contact.
What are Closest-Packed Structures? What are the 2 types?
Stacking atoms on top of one another; more conceptual!
Hexagonal Closest Packing and Cubic Closest Packing.
Hexagonal Closest Packing and Cubic Closest Packing:
Just have to look at the examples in the book!!! ch.12!
What are Molecular Solids?
Solids that are composed of molecules. The Lewis Structure plays a large role in stability.
What are Ionic Solids? Melting points?
Cations and Anions (salt) held together by ionic bonds. High melting points!
What are Atomic Solids?
Composite particles of individuals atoms. Each version of atomic solids are held together by a different force!
If a question on the 3 Atomic Solids, Week 14 Ch. 12 Notes!!!
YES.
Differences between Unit Cells and Ionic Solids?
There are Cations and Anions in Ionic solid structures, as opposed to just one atom.
What is Coordination Number? How does it relate with atomic radii
Max interactions between cations and anions. Larger atomic radii restrict coordination number. EX- NaCl, large Cl.
How are unit cells affected by the charge ratio?
When the ratio is not 1:1 in a molecule, etc., must accommodate new ratio to keep charge neutrality.
What do Network Covalent Atomic Solids have? What are some examples?
Some of the highest melting points of all substances. Carbon and its different forms/allotropes, etc.
What are some Carbon based forms/allotropes?
Graphite, Coal, Diamond, Fullerenes, Nanotubes, etc.
What are carbon nanotubes?
Carbon6 rings in hexagonal shape, shaped as a tube. There are Single walled (SWNT) and Multi-walled (MWNT) nanotubes.
What can be done with Multi-walled nanotubes (MWNT)?
They can be “cut up” into Graphene nanoribbons. This is what carbon fiber is!
What are silicates, why are they unique?
Molecules compose 90% of earths core. They have one lone electron on the Oxygen.
What is the difference between valence bonds and conduction bonds?
Valence bonds are occupied/ bonding orbitals. Conduction Bonds are empty/ anti-bonding orbitals.
What is a Band Gap?
The energy required for an e- to be promoted from valence to conduction.
What are the 3 types of band gaps?
Conductor: NO energy gap.
Semiconductor: Small energy gap.
Insulator: Large energy gap.
