1. Structures and Types of Solids

2. TWO TYPES OF SOLIDS 1. Crystalline solids
highly regular arrangement of their particles
crystals- at microscopic level

3. How are they crystals?
Lattice - 3-D system of points indicating position of ions, atoms or molecules that make up the substance

4. Unit cell
Smallest repeating pattern of the lattice- extend in all directions for the structure

6. Three Types of Cystalline Solids
Component of Lattice
Bonding
Example
Ionic Solids
Have ions at lattice points
Ionic
NaCl
Molecular Solids
Have molecules at lattice points
Dipole-Dipole and/or LDF
H2O
Atomic Solids
Have atoms at lattice points
LDF, directional covalent or metallic
C, B, Si
and all metals

7. Two types of solids
2. Amorphous solids- considerable disorder in their structure
EX- glass- liquid that is “frozen in place”

8. Bonding models for metals
Model must account for physical properties:
A. shape can be changed fairly easily- malleable and ductile

9. Bonding models for metals
B. durable
C. high melting points

10. Bonding models for metals
Indicates the bonding is STRONG and NONDIRECTIONAL
or difficult to separate metals atoms, but easy to move them

11. The model is... Electron “sea”model
metal cations in sea of e- (mobile e- for conductivity and cations can be moved around when hammered

13. Metal alloys!
Metals introduced into the crystal structure of other metals

14. Alloy
A substance that contains a mixture of elements and has metallic properties

15. Two types of alloys
Substitutional alloy- some of the host metal atoms are replaced by other metal atoms of similar size

16. Substitutional alloys
EX: Brass (1/3 of copper atoms replaced with zinc)
Pewter (85%Sn, 7%Cu, 6%Bi, 2%At)

17. Two types of alloys
Interstitial alloy- formed when some of the holes in a close packed metal structure are occupied by smaller atoms

18. Interstitial alloy EX: Steel (carbon atoms into iron)
Strengthens iron by adding strong directional bonds