Quantum MechanicsThrough the Looking Glass

Rutherford Bohr-Planetary Model

This is how the model of the atom has developed so far:

Correcting Bohr’s Planetary Model…using the Photoelectric Effect

Louis DeBroglie’s insight:If light radiation can have a particle nature

then why can’t particles have a wavelike nature?

If electrons are particles

Electrons must have a wavelike nature

= h mv

Werner Heisenberg (1901-1976)

There is an uncertainty in either the position or the momentum of an electron that cannot be reduced beyond a certain minimum level

Heisenberg’s Uncertainty Principle

Is Shrodinger’s cat dead or alive?

The Quantum Mechanical Model

Describes the wave properties of electrons

and regions of space surrounding the nucleus

Called orbitals

Where there is a high probability offinding electrons

Describing an electron’s address

Bohr’s model places the electron ina quantum energy level (n)

Bohr-Planetary Model

Describing an electron’s addressusing the Quantum Mechanical Model

Electrons exist in orbitals

A collection of orbitals with the same energyis called an electron shell designated (n)

1st quantum #-principle quantum number (n) n = (1,2,3,…, ) describes shell or energy level

Describing an electron’s addressusing the Quantum Mechanical Model

2nd quantum # - azimuthal number (l), value 0 to n-1 describes sublevel

3rd quantum # - magnetic number (ml), value = l to 0 to-l The orientation of the orbital in space

4th Quatum # - Spin (ms), value is + or – ½, describes the spin

The first energy level (n = 1) is constructed from a single orbital (l = 0), also designated ‘1s’,

which is spherical ( ml = 0)

The second energy level (n = 2) is constructed from a single orbital (l = 0) also designated ‘2s’

which is spherical ( ml = 0)

The third energy level (n = 3) is constructed from a single orbital (l = 0) also designated ‘3s’

which is spherical ( ml = 0)

Energy level ‘n = 2’ is more complex than energy level ‘n =1’ and is constructed from

two kinds of orbitals

The innermost part of ‘n =2’ consists of asingle spherical orbital designated ‘2s’

The outermost part of ‘n = 2’ consists of three orbitals which are not spherical, (l = 1)

Each dumbbell-shaped orbital (l = 1), also designated ‘2px, 2py,2pz’is oriented along

the x, y, and z axes ( ml = -1, 0, 1)

Like the ‘s’ orbital, the ‘p’ orbitals also repeat in subsequent energy levels

Energy level ‘n = 3’ is more complex than energy level ‘n =1’ or ‘n = 2’ and consists of an

innermost spherical orbital designated ‘3s’

The middle part of ‘n = 3’ consists of three dumbbell-shaped orbitals , (l = 1)

The outermost part of ‘n = 3’ consists of five orbitals which are also not spherical, (l = 2)

Each four-lobed orbital (l = 2), also designated ‘3 d orbital ’is oriented along different

planes ( ml = -2, -1, 0, 1, 2)

Like the ‘s’ and ‘p’ orbitals, the ‘d’ orbitals also repeat in subsequent energy levels

Energy level ‘n = 4’ is more complex than energy level ‘n =1, 2, or 3’ and consists of an

innermost spherical orbital designated ‘4s’

The lower middle part of ‘n = 4’ consists of three dumbbell-shaped orbitals , (l = 1)

The upper middle part of ‘n = 4’ consists of five orbitals which are also not spherical, (l = 2)

The outermost part of ‘n = 4’ consists of seven orbitals, also designated ‘f ’ orbitals, which are also not spherical, (l = 3)

In fact, they are a real

nightmarenightmare ( ml = -3, -2, -1, 0, 1, 2, 3)

Describing an electron’s address

Quantum Mechanics: Where ever you go...there you are!

Schwartzchild’s Radical

which of the following is not an allowable quantum number1. 4,4,3,1/22. 3,2,2,13. 5,2,-1,-1/2

What are the maximum number of electrons allowed that have the quantum

numbers designated?1. n=32. n=3, l=23. n= 3, l=2, ml = 1

4. n= 3, l=2, ml = 1, ms = 1/2

Which of the following are in an excited state and what element do they represent?

1. 1s22s22p63p64s23d104p65s24d105p6

How many unpaired electrons are in each of the following.

CrFe3+

Cl1-