Download Quantum Mechanical Model - Elmwood Park Memorial Middle School

Quantum Mechanical Model
Do Now •  Take out your answers to the introduc4on reading. •  These slides are on the webpage if you would like them. •  Heisenberg Uncertainty Principleit is impossible to determine both the position
and velocity of extremely small particles at the
same time
Why?
Think about how particles are detected or how your eyes work…
Quantum Mechanical Model
•  From Heisenberg’s principle we know that we can’t
exactly locate electrons
•  We can determine probable locations… general areas
•  Schrodinger created an equation for solving these
locations, but it has only been completely solved for
hydrogen
Why hydrogen? The modern model of the atom is similar to Bohr s Model.
The main difference is that there are no ORBITS!
Address??
•  Yep, the new model creates an
approximate address for each electron in
the atom.
•  The address will have 4 parts just like a
standard postal address
–  State
–  City
–  Street
–  House number
Quantum Numbers
•  Principal Quantum Number (n)
–  Energy levels
–  Distance from the nucleus
–  Size of the electron location
Whole numbers n= 1,2,3…
These are the rings from Bohr s model!
The total number of electrons in the energy level
is equal to 2n2
SIZE
n=1
n=2
n=3
•  Angular Momentum Quantum Number (l)
Sublevel
–  Shape of the electron location
–  Each energy level can have “n” sublevels
Whole numbers starting from 0
l= 0,1,2,3…n-1
How many sublevels would be found on energy level 3?
Shapes
l value
shape
name
0
spherical
s sublevel
1
peanut
p sublevel
2
?
d sublevel
3
?
f sublevel
l = 0 (s orbitals)
l = 1 (p orbitals)
l = 2 (d orbitals)
•  Magnetic Quantum Number (m)
•  Orbitals (electron locations)
–  Direction or orientation, determines the
number of orbitals
m = -l to +l including 0
Example- l=2 m= -2,-1,0,1,2
Orbitals
•  How many orbitals would each of the
sublevels have?
Orbital Directions
ml = -1
ml = -2
ml = 0
ml = -1
ml = 0
ml = 1
ml = 1
ml = 2
•  Spin Quantum Number (s)
•  Direction of electron spin
–  Either clockwise or counterclockwise
s = ½ or – ½
•  Pauli Exclusion principle
no two electrons in the same atom have the same four
quantum numbers
Based on what you have learned today,
how many electrons can an orbital hold?
Electron Addresses
•  Each electron will have a unique set of 4
quantum numbers
•  For exampleAn electron on the 3rd energy level, p sublevel,
second orbital, spinning clockwise
n= 3, l= 1, m= 0, s= 1/2