1. Solids
Ch. 12

2. 3 Most Common Phases of Matter

3. Crystal Structure

4. Crystal Structure
Metals, salts, and most minerals are made up of crystals!
In 1912 physicists used x-rays to confirm that each crystal is a 3D orderly arrangement of atoms
It took us quite awhile to actually see it!

5. Max von Laue
Discovered that a beam of X-rays directed upon a crystal is diffracted, or separated, into a specific pattern
X-ray diffraction patterns on photographic film show crystals to be neat, uniform lattices

6. Metals
All metals contain a jumble of many crystals, each almost perfect, with the same regular lattice
These metal crystals can be seen when a metal surface is etched, or cleaned with acid

7. Amorphous

8. Amorphous Solids Noncrystalline solids are amorphous
Atoms and molecules in a solid are distributed randomly
Rubber, glass, and plastic all lack an orderly, repetitive arrangement at a molecular level
You can tell because rubber is elastic, glass flows when stressed

9. 4 Principal Types of Bonding in Solids
Atoms are tied together by electrical bonding forces. For solids this includes:
Ionic
Covalent
Metallic
Van der Waals’
Which of these is weakest?

10. Mini Quiz
How does the arrangement of atoms in a crystalline substance differ from that in a noncrystalline substance?
What evidence can you cite for the microscopic crystal nature of certain solids?
3) For macroscopic crystal nature of certain solids?

11. Density Depends how much of Each you have! Iron is denser though
Is iron heavier than wood?
Depends how much of
Each you have!
Iron is denser though

12. Density
The masses of the atoms and the spacing between them determine the density of materials
A measure of the compactness of matter, OR
how much mass occupies a given space OR
the amount of mass per unit volume

13. Density Formula

14. Density The density is a property of a material
Therefore it doesn’t matter how much of the material you have
Density of a material depends upon the masses of the individual atoms that make it up and the spacing between those atoms

15. Units for Density g/cm3 When we do weight density then we use N/m3
1cm3 = 1mL
When we do weight density then we use N/m3
because a 1kg body has a weight of 9.8N, weight density is numerically 9.8 x mass density

16. Mini Quiz Is iron or wood heavier? Explain!
Density is a ______________ of a material. This means it doesn’t depend on how much of the material you have.
What is one of the correct units we might use for density?

17. Elasticity
When an object is subjected to external forces, it undergoes change in size, or shape, or both.
The change depends on the arrangement and bonding of the atoms in the material
Example: A spring can be stretched or compressed by an external force

18. Inches and pounds… yuck who even uses those?
Elasticity
A weight hanging on a spring stretches the spring
Additional weight stretches the spring ___________
Further
Inches and pounds… yuck who even uses those?

19. Elasticity
If the weights are removed, the spring returns to its original length
We say that the spring is elastic

20. Examples of Elasticity
When a batter hits a baseball, the bat temporarily changes the ball’s shape
An archer, about to shoot an arrow, first bends the bow, which springs back to its original shape when the arrow is released.