Chapter 4 : quantum mechanics
10/7/2022
CHEM 121 111
, Fundamentals of Quantum Mechanics
Wave nature of matter
Interference: when two waves collide (one raises in amplitude
while one is decreasing in amplitude)
✗ =h p=mv Kinetic energy = 1/2 mv
&
p
-34
h= Planks consant (6.626 x 10 ) Kg m/s
p= mass x velocity Kg m/s (Momentum)
m= mass in kilograms
v= 3.30 x 10 m/s (Velocity)
6
✗ = wavelength
Electrons both behave as particle and waves
When mass increase wavelength decreases:
Only small objects like (an electron) are defined by
quantum mechanics. Small objects like electrons can
oscillate. Big objects will not oscillate because their mass
exceeds that of the de broglie wavelength
•Mr
This is why we don’t see something
Barnum big (like a tennis ball) oscillate
⑧ 0 0. # @ = Crystal particles
O O O Wave of large wavelength will hit many crystal particles
D
•
Tr Smaller wavelengths will diffract
Smallest wavelength will pass though the
particles
Tip:
When any question mentions atomic crystals, USE De Broglie
wavelength
10
Conversion for angstrom A : 1.00x 10
-
"
conversion for Joules electron ) Joules )
,o↓
[ joules per
=
6- Od ✗ 10 cavogadro 'S constant
✗ ✗
e- e- ,
1
10/7/2022
CHEM 121 111
, Fundamentals of Quantum Mechanics
Wave nature of matter
Interference: when two waves collide (one raises in amplitude
while one is decreasing in amplitude)
✗ =h p=mv Kinetic energy = 1/2 mv
&
p
-34
h= Planks consant (6.626 x 10 ) Kg m/s
p= mass x velocity Kg m/s (Momentum)
m= mass in kilograms
v= 3.30 x 10 m/s (Velocity)
6
✗ = wavelength
Electrons both behave as particle and waves
When mass increase wavelength decreases:
Only small objects like (an electron) are defined by
quantum mechanics. Small objects like electrons can
oscillate. Big objects will not oscillate because their mass
exceeds that of the de broglie wavelength
•Mr
This is why we don’t see something
Barnum big (like a tennis ball) oscillate
⑧ 0 0. # @ = Crystal particles
O O O Wave of large wavelength will hit many crystal particles
D
•
Tr Smaller wavelengths will diffract
Smallest wavelength will pass though the
particles
Tip:
When any question mentions atomic crystals, USE De Broglie
wavelength
10
Conversion for angstrom A : 1.00x 10
-
"
conversion for Joules electron ) Joules )
,o↓
[ joules per
=
6- Od ✗ 10 cavogadro 'S constant
✗ ✗
e- e- ,
1
