1. Solids and Liquids
Physical Properties of Liquids

2. Atoms or molecules do not interact with each other, except for collisions
Condensed matter:
Atoms or molecules are closely packed and interact with each other

3. Liquids have a permanent network of intermolecular bonds that are continuously made and broken
liquids hold together
liquids can flow

4. flow: the ability of a liquid to move and change shape under a force, such as gravity.

5. Energy of solid vs. liquid
On the molecular level, liquids are like amorphous solids.
However, higher energy in liquids causes intermolecular bonds to break quickly after they are formed.

6. Liquid SiO2 doesn’t remember whether it came from quartz or glass!
Quartz a crystalline form of SiO2
Glass an amorphous form of SiO2
slow cooling
fast cooling
Liquid SiO2 doesn’t remember whether it came from quartz or glass!

7. Liquid SiO2 doesn’t remember whether it came from quartz or glass!
Quartz a crystalline form of SiO2
Glass an amorphous form of SiO2
melting
melting
Liquid SiO2 doesn’t remember whether it came from quartz or glass!

8. Physical properties Cohesion
The property of a liquid that causes it to hold together
Attractive forces between molecules in a liquid cause liquid drops to come together as tight as possible in a perfect sphere

9. Cohesion Cohesion keeps rain drops together as they fall on the ground
Liquid mercury (Hg) is very cohesive

10. Physical properties Adhesion Cohesion
The property of a liquid that causes it to stick to surfaces
Geckos use the property of adhesion to stick to surfaces such as the walls and ceilings of houses

11. When something is “wet,” we mean that liquid is adhering to it
Adhesion
When something is “wet,” we mean that liquid is adhering to it
Different surfaces have different wettability: they can be wet by the same liquid differently

12. Adhesion
When something is “wet,” we mean that liquid is adhering to it
Different surfaces have different wettability: they can be wet by the same liquid differently
Liquids that adhere to things very well are called adhesives
They are commonly used as glues or put onto tape to make it sticky

13. Cohesion or adhesion? Water is more adhesive
It sticks to the sides of the glass
Mercury is more cohesive
It sticks to itself more
Meniscus

14. Plants use capillary action to draw water up from roots to leaves.
Water passes through these tubes
Plants use capillary action to draw water up from roots to leaves.
Even very tall trees move water this way.
capillary action: an effect where liquids is pulled up a thin tube by adhesion

15. Physical properties Viscosity Cohesion Adhesion
The resistance of a liquid to flow under an applied force
Honey

16. Viscosity Viscosity is a measure of resistance to flow.
Snails and slugs use mucus, a very viscous substance, to help them stick to surfaces and move.

17. Viscosity Viscosity depends on the strength of intermolecular bonds
Water is a polar molecule with strong intermolecular forces.
Water is more viscous than nonpolar liquids, such as liquid nitrogen

18. Viscosity Viscosity depends on the strength of intermolecular bonds
the shape of the molecules
Oils are more viscous because the long-chain molecules can be easily entangled, and this slows down the flow

19. Physical properties Surface tension Cohesion Adhesion Viscosity
A property of liquids to resist having their surface broken

20. Surface tension measures the energy it takes to break the surface of a liquid.
surface tension: a property of liquids to resist having their surfaces broken, usually measured in J/m2.

21. Surface tension Soaps are medium-length chains with - one polar end
- and one non-polar end
The polar end adsorbs to the water surface, and this breaks up the surface tension
Soaps work by partially lowering surface tension

22. Liquids have a permanent network of intermolecular bonds that are continuously made and broken
This results in interesting physical properties:
Cohesion
Adhesion
Viscosity
Surface tension