1. States of Matter, and Phase Change
Chapter 13 L

2. Liquids

3. Characteristics Density & Compression Fluidity
Much denser then gases (and vapors)
Compression requires large amounts of pressure
Able to flow (mix with other liquids)
Not as fluid as gases
Because of intermolecular forces

4. Characteristics (….continued)
Viscosity
Surface tension
Resistance to flowing
Because they are closer together, attractions between them will resist movement
Controlled by
attractive forces
Shape of molecules
Temperature
Measure of the inward pull of particles in the interior
Greater attraction between particles, the higher the surface tension

5. Characteristics (….continued)
Capillary action
Cohesion – attraction between identical particles
Adhesion – attraction between molecules that are different
Together cause a liquid to move into the small spaces between other molecules
Why if you drop a corner of toilet paper in the toilet, the whole sheet gets soaked

6. Solids

7. Characteristics Far denser then liquids or gases
Molecules arranged in crystalline lattices
Types of Crystalline Solids
Type
Unit particles
Characteristics of solid phase
Examples
Atomic
Atoms
Soft to very soft; very low melting points, poor conductivity
Group 8A elements
Molecular
Molecules
Fairly soft; low to moderately high melting points; poor conductivity
I2, H2O, NH3, CO2, C12H22O11
Covalent Network
Atoms connected by covalent bonds
Very hard; very high melting points; often poor conductivity
Diamond (C), and quartz (SiO2)
Ionic
Ions
Hard; brittle; high melting points; poor conductivity
NaCl, KBr, CaCO3
Metallic
Atoms surrounded by mobile valence electrons
Soft to hard; low to very high melting points; malleable and ductile; excellent conductivity
All metallic elements

8. Forces of attraction

9. Intermolecular forces
forces between different molecules
London forces (AKA dispersion forces)
VERY weak attraction between non-polar covalent molecules
Temporary dipole moment
Electrons fly around the nucleus, therefore it is possible that any given moment they could cause a dipole to form
Since electrons repel one another they can force this dipole on other atoms
is only significant when molecules are very close
Greatest between identical non-polar molecules

10. Induced Dipole moment

11. Intermolecular forces (….continued)
Dipole-dipole forces
Hydrogen Bonds
Medium strength force between polar molecules
Attraction is based on mass and polarity
Smaller mass = more attraction
Larger polarity = more attraction
Strongest of intermolecular forces
Attraction between H+ and O-2, F-1, N-3.
When hydrogen is bound to any of those 3 it will be attracted to other molecules
(+) H lines up with (-) cation
Why water has such a high boiling point & surface tension

13. Phase changes

14. Phase change

15. Words and formulas Heat of Vaporization (DHvap):
Heat required to vaporized 1 mole of a liquid
Direct inverse of heat of condensation
(DHvap = -DHcond)
Heat of Fusion (DHfus)
Heat required to melt 1 mole of a solid
Direct inverse of heat of solidification
(DHfus = -DHsolid)

16. Vapor Pressure Vaporization
D of a liquid into gas
Evaporation – vaporization of surface liquid
As liquid becomes a vapor, it exerts a pressure on the surface of the liquid
A substance boils when its vapor pressure is equal to or greater than atmospheric pressure
DEMO!

17. Phase Change Diagram

18. Phase Change and Temp.
While a substance it changing states there is NO change in T until all of the substance is in the next phase