Chapter 13 The Chemistry of Solids
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Chapter 13 The Chemistry of Solids Types of Solids • Metals • Network • Ionic • Molecular • Amorphous
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Chapter 13 The Chemistry of Solids. Types of Solids Metals Network Ionic Molecular Amorphous. Chapter 13 The Chemistry of Solids. Types of Solids Examples Metals Copper Network Quartz Ionic NaCl Molecular CO 2 , CI 4 Amorphous glass, polyethylene. - PowerPoint PPT Presentation
Transcript of Chapter 13 The Chemistry of Solids
Chapter 13 The Chemistry of SolidsTypes of Solids
• Metals• Network• Ionic • Molecular• Amorphous
Chapter 13 The Chemistry of SolidsTypes of Solids Examples
• Metals Copper• Network Quartz• Ionic NaCl • Molecular CO2, CI4• Amorphous glass, polyethylene
Types of Solids Characteristics
• Metals Copper - malleable
• Network Quartz – non-malleable
• Molecular sulfur (S8)• CO2, CI4 – low melting pt
• Ionic & muscovite– cleaves easy Network, Layered structure
The Chemistry of SolidsWhat characteristic do these solids share?
The Chemistry of SolidsWhat characteristic do these solids share?
Repeating Structural Patternother terms:LatticeArrayCrystal Structure orCrystal Lattice
The Chemistry of SolidsUNIT CELL is the smallest piece of the pattern that generates the lattice.
UNIT CELL is a conventional choice.May have several unit cells possible,Different in shape and/or size.
Translation directions
The Chemistry of SolidsUNIT CELL is a conventional choice.May have several unit cells possible,Different in shape and/or size.
Three Types of Cubic Unit Cells
a
cb
Simple Cubic Body Centered Cubic
Face CenteredCubic
These Three Cubic Unit Cells are Structuresof most Metallic Elements(also hexagonal, hcp, to be seen Friday)
Cu, Ag, Au are all fccCr, Mo, W are all bccOnly Po is simple cubic (rare— why?)
Simple Cubic Body Centered Cubic
Face CenteredCubic
One result of a metal’s “choice” to adopt a cubic, bcc or fcc lattice are metal properties
Simple Cubic Body Centered Cubic Face Centered Cubic
Packing a Square Lattice:
Makes a simple cubic cell
Can you pack spheres more densely?
The Rhomb is the Unit Cell Shapeof Hexagonal Lattices
Closest Packing: hexagonal layers build up 3D solid
Find the triangular gaps in the Pink layer
Note how layers “sit” on top of each other:
The Cyan layercovers the “up”triangles of thePink layer
The Yellow layercovers the “down”triangles of thePink layer
This packing sequence is A B C A B C,Where B and C cover different “holes” in A
BC
A
BC
A
BC
A
BC
APa
ckin
g di
rect
ion A
C B A C B A
ccp CubicClosestPacking:A B C A B C …
Packing direction
CCP viewed unit cell;
LOOK! It’s face centered cubic!!! CCP = FCC!!
….mmmMMM
CCP viewed as packing layers
AB
C
CBA
Effect of addedatoms andgrainson metal structure.
Smaller atom like C in iron
Larger atom like P in iron
Second crystal phasesprecipitated
Defects and grain boundaries “pin” structure. All these inhibit sliding planes and harden the metal.
Defectsin metal structure
From Metals to Ionic Solids
Will ionic solids pack exactly like metallic solids?
From Metals to Ionic Solids
Build up Ionic Solids conceptually like this:• assume Anions are larger than Cations, r- > r+• pack the Anions into a cubic lattice: ccp, simple or bcc• add Cations to the interstitial spaces (“Mind the gap!”)
2 x r-
2 x r-
r- + r+
The Simplest Ionic Solid is CsCl, simple cubic
Start withsimple cubicUnit cell of Cl- ions
Then add one Cs+ in center
Z =C. N. (Cs) =
How to draw this
How to make NaCl: start with fcc unit cell of Cl- ions
Add Na+ in between
Add Na+ in between, everywhere
Z =C. N. (Na) =
