 I. Kinetic (molecular) Theory – explains properties of (s), (l), (g), in terms of forces between particles & the E they possess…..the MOTION of the particles – it says that particles (atoms & molecules) are in constant motion  Vid KMT Vid KMT

 1. matter composed of tiny particles  2. particles in constant motion  3. total E of colliding particles remains constant (some particles lose E & some gain E in collisions ….the collisions are ELASTIC which means they don’t lose any kinetic energy)

 1. KE = ½ mv 2  2.Units are Joules. kgm 2 /s 2

 1. The acceleration produced by a net force is directly proportional to the force that caused it & in the same direction.  (if F ↑ then a ↑ ) AND

 2.The acceleration produced by a force is inversely proportional (if m ↑ then a ↓ )to the mass of the object.  3. a = F/m or F = ma m = F/a

 A. Gas particles are far apart relative to their size  B. Collisions between gas particles & container (cause pressure) are elastic  C. Gas particles are in continuous rapid, random motion (they have lots of KE!)

 D. No forces of attraction between gas particles (no IMF’s)  E. Average KE of gas particles depends on the Temperature of the gas … KE = ½ mv 2

 1. Since m is the mass of the particle & all the particles of a specific gas have the same mass then the KE is completely dependent on the speed of the particle.  *** so an increase in Temp means an increase in speed & vice versa

 2. All gases at the same temp have the same avg KE SO lighter gas particles have higher avg. speeds than heavier gas particles.  Look at your chart that shows the sizes of the atoms

Gases expand to fill any container.  random motion, no attraction  no set shape Gases are fluids (like liquids).  no attraction Gases have very low densities.  no set volume = lots of empty space Courtesy Christy Johannesson

 an IDEAL gas is an imaginary gas that perfectly fits all the “rules” of the kinetic theory…..  a REAL gas does not behave completely according to the “rules” of the kinetic theory, but this is usually only noticeable at extreme pressure & low temp

 A. Gases are easy to expand (volume)---gas molecules don’t strongly attract each other  B. Gases are easy to compress --- gas molecules don’t strongly repel each other  C. Gases have densities that are about 1/1000 of their solid or liquid densities --- gas molecules are much farther apart in gases than in liquids or solids

GGases can be compressed. nno set volume = lots of empty space GGases undergo diffusion & effusion. rrandom motion Courtesy Christy Johannesson

 D. Gases completely fill their containers --- gas molecules are in constant motion  1. fluidity – gas particles glide easily past each other or FLOW

 E. Hot gases leak through holes faster than cold gases --- the hotter the gas, the faster the molecules are moving  1. diffusion – random movement of particles from an area of greater concentration to an area of lesser concentration  2. effusion – process through which gas particles pass through a small opening  Vid review gases Vid