1. Kinetic Molecular Theory
(KMT)
Solids
Liquids
Gases
Hard to compress with high densities
Definite shape and definite volume
NOT easy to diffuse
Hard to compress and less dense
NO fixed shape but definite volume
Fairly easy to diffuse
Easily compressed with low densities
NO fixed shape, NO fixed volume
Easy to diffuse

2. C11-1-05 KINETIC MOLECULAR THEORY
OUTCOME QUESTION(S):
C KINETIC MOLECULAR THEORY
Describe the properties of gases, liquids, solids and plasma.
Include: compressibility, diffusion
Use the Kinetic Molecular Theory to explain properties of solids, liquids and gases.
Include: intermolecular forces, elastic collisions, kinetic energy,
temperature and particle motion
Understand the various phase changes in terms of KMT.
Include: sublimation, deposition, evaporation, condensation
Vocabulary & Concepts 
Intramolecular Intermolecular
Crystalline Amorphous

3. Kinetic Molecular Theory Theory explaining how gas particles behave.
If we know how gases behave, we can make predictions about liquids and solids
The major assumptions (postulates):
Postulate 1:
Postulate 2:
Postulate 3:
Postulate 4:
Collisions result in no change in energy and the average kinetic energy (KE) of a sample depends only on temperature.
Particles constantly move and collide with other particles
or the container.
Particles are very small and most of the volume of a gas is empty space.
There are no forces of attraction between particles or the container.
Bernoulli
Maxwell
Boltzmann
Van der Waals

4. Actual Particle Volume
Bernoulli
Particles are very small and most of the volume of a gas is empty space.
Postulate 1:
Gases
Easily compressed with low densities
NO fixed shape, NO fixed volume
Easy to diffuse
99%
Empty Space
Volume of Gas
Actual Particle Volume
This postulate isn’t surprising – we know from experience that gases are easily compressed and mostly empty space (we do walk through it…)

5. Particles constantly move and collide with other particles
or the container.
Postulate 2:
Maxwell
Gases
Easily compressed with low densities
NO fixed shape, NO fixed volume
Easy to diffuse
Gas particles collide with the sides of the container, and exert a force.
(gas pressure)
Particles are in constant, random motion and are limited only by collisions with the walls of the container

6. Maxwell and Boltzman:
An object in motion has kinetic energy – KE is directly related to particle speed.
Not all particles have the same energy level at the same temperature
average
Temperature is the measure of the average kinetic energy of all particles in the sample
Some particles have high energy, some have low – most have an average amount…
Maxwell
Connect: An increase in temperature (↑KE) manifests as an increase in particle motion which increases collisions which is measured by increasing gas pressure .
Boltzmann

7. No gain or loss of kinetic energy
Boltzmann
Collisions result in no change in energy and the average kinetic energy (KE) of a sample depends only on temperature.
Postulate 3:
All collisions between particles, and with their container, are elastic.
No gain or loss of kinetic energy
Collisions must be elastic – have you watched an inflated ball suddenly contract (lose energy) or expand (gain energy) when just sitting there? NO

8. Intramolecular forces – (ie. bonds)
There are two types of attractive forces that affect particles:
Intramolecular forces – (ie. bonds)
(within) + Na - Cl
Intramolecular H O δ- δ+
Intermolecular
2. Intermolecular forces – (attraction)
(between)
Usually gas particles have enough kinetic energy to whiz by each other without being affected by intermolecular forces (IMF)

9. There are no forces of attraction between particles or the container.
Postulate 4:
Van der Waals
Note: Kinetic theory assumes that all gases behave ideally; but, we know this is not always the case. 
Gases
Easily compressed with low densities
NO fixed shape, NO fixed volume
Easy to diffuse
There can’t be much attraction between gas molecules normally since particles expand out and diffuse easily

10. Kinetic Molecular Theory for Gases
Easily compressed with low densities.
Particles of a gas must be far apart and loosely packed
2. NO fixed shape, NO fixed volume.
Particles are in free, constant, random motion involving elastic collisions
Easy to diffuse.
Intermolecular attraction (IMFs) is weak,
affording particles no restrictions

11. Kinetic Molecular Theory for Liquids
Hard to compress and more dense than gases.
Particles closer together and more densely packed
NO fixed shape, but definite volume.
IMFs are strong enough to allow some particle movement but limit particle distance
Fairly easy to diffuse.
Intermolecular attraction (IMFs) is stronger than in gases, restricting particle flow

12. Kinetic Molecular Theory for Solids
Hard to compress with high densities.
Particles very close together and very densely packed
Definite shape and definite volume.
Strongest IMFs severely restrict particle movement and control distance
NOT easy to diffuse
Intermolecular attraction (IMFs) is the strongest,
completely restricting particle flow

13. Solids come in two main forms: crystalline and amorphous.
Crystalline – particles arranged in a geometric, three-dimensional pattern.
Crystal structure and symmetry play a role in determining other physical properties

14. Amorphous – particles have an irregular arrangement.
Amorphous has Greek roots meaning “without form”
Same atoms…different physical properties
Other examples of amorphous: wax, rubber, plastic

15. Solid structures can be held by ionic attraction or covalent intermolecular forces.
Ionic (ions)
Polar (dipoles)
C6H12O6
(sugar)
NaCl
Melts at 801oC
Melts at 186oC
IMFs can be stronger or weaker, but attraction is typically strongest in ionic solids – as evidence in melting points

16. C11-1-05 KINETIC MOLECULAR THEORY
CAN YOU / HAVE YOU?
C KINETIC MOLECULAR THEORY
Describe the properties of gases, liquids, solids and plasma.
Include: compressibility, diffusion
Use the Kinetic Molecular Theory to explain properties of solids, liquids and gases.
Include: intermolecular forces, elastic collisions, kinetic energy,
temperature and particle motion
Understand the various phase changes in terms of KMT.
Include: sublimation, deposition, evaporation, condensation
Vocabulary & Concepts 
Intramolecular Intermolecular
Crystalline Amorphous