1. CHAPTER 16
Solids and Liquids
16.1 The Properties of Solids

3. Macroscopic physical properties ultimately come from the microscopic world of molecules and chemistry

4. Physical properties Density The amount of matter per unit volume
Example:
Steel has a density of 7.8 g/cm3 whereas polyethylene plastic has a density of 2 g/cm3

5. Density The density of a substance is affected by two factors:
1) the mass of the molecules or atoms of which the substance is made
Atomic weight of platinum (Pt): 195 g/mole
Molecular weight of polyethylene: >200,000 g/mole

6. Density The density of a substance is affected by two factors:
1) the mass of the molecules or atoms of which the substance is made
Atomic weight of platinum (Pt): 195 g/mole
Molecular weight of polyethylene: >200,000 g/mole
2) how closely the atoms or molecules are packed together

7. Density The density of a substance is affected by two factors:
1) the mass of the molecules or atoms of which the substance is made
Atomic weight of platinum (Pt): 195 g/mole
Molecular weight of polyethylene: >200,000 g/mole
2) how closely the atoms or molecules are packed together

8. Density The density of a substance is affected by two factors:
1) the mass of the molecules or atoms of which the substance is made
Atomic weight of platinum (Pt): 195 g/mole
Molecular weight of polyethylene: >200,000 g/mole
2) how closely the atoms or molecules are packed together
Polyethylene has a lower density than platinum

9. Physical properties Hardness Density
The resistance of a material to small deformation, like scratches
Example:
Glass is harder than copper, and copper is harder than plastic

10. Hardness
How easy is it to deform a material by moving molecules out of their places?
Diamond is the hardest known substance
The only thing that can cut a diamond is another diamond!
Diamond is a network covalent substance

11. Hardness
The Mohs hardness scale is a scale used for describing hardness
Deformation per unit force
Mohs hardness scale

12. Physical properties Elasticity Density Hardness
The ability to stretch and rebound without breaking
Example:
Rubber is often very elastic, and glass is hardly elastic at all

13. Physical properties Transparency Density Hardness Elasticity
The ability for light to pass through a material
Example:
Glass and plastic can be transparent, whereas rubber and metals are typically opaque

14. Physical properties Strength Density Hardness Elasticity Transparency
The amount of force a material can withstand before breaking
Example:
Steel is much stronger than aluminum, and aluminum is stronger than rubber or plastic

15. Strength Strength has three primary aspects:
1) How much will a material deform under a given force?
Elastic materials such as rubber and soft plastics can deform under a great deal under a relatively small pressure

16. Strength Strength has three primary aspects:
1) How much will a material deform under a given force?
2) Does a material stretch before breaking or does it snap suddenly?

17. Strength Strength has three primary aspects:
1) How much will a material deform under a given force?
2) Does a material stretch before breaking or does it snap suddenly?
Metals are typically ductile. Gold can be hammered into very thin sheets without breaking
Ceramic and glass are brittle materials. So are ionic solids, including most mineral crystals and rocks

18. Strength Strength has three primary aspects:
1) How much will a material deform under a given force?
2) Does a material stretch before breaking or does it snap suddenly?
3) How much force can a material ultimately withstand before it breaks?
Most materials will stretch a certain amount, then snap

19. Physical properties Electrical conductivity Density Hardness
Elasticity
Transparency
Strength
Electrical conductivity
Copper wire (conductor)
Plastic (insulator)
The ability for electrical current to flow through a material
Example:
Copper and aluminum are excellent conductors, but glass, rubber, and plastic are insulators

20. Physical properties Thermal conductivity Density Hardness Elasticity
Transparency
Strength
Electrical conductivity
Thermal conductivity
The ability for heat to flow through a material
Example:
Metals are good heat conductors; rubber and plastics are moderate heat conductors

21. Macroscopic physical properties come from the microscopic world of molecules and chemistry
Density
Hardness
Elasticity
Transparency
Strength
Electrical conductivity
Thermal conductivity
Diamond is a network covalent substance