Download The Quantum Model

THE QUANTUM MODEL
Section 4.2
BELL WORK
1.
2.
3.
4.
5.
6.
7.
A spherical electron cloud surrounding an atomic
nucleus would best represent a _____ sublevel.
Any one (1) atomic orbital can hold a maximum of
___ electrons
An energy level of n=2 contains ____ orbitals.
An energy level of n=4 contains ____ orbitals.
An energy level of n=3 can hold ____ electrons.
An energy level of n=1 can hold ____ electrons.
An f - sublevel can hold ____ electrons.
BELL WORK
Define Diffraction.
 Define Interference.
 Define Orbitals.
 List the 4 quantum numbers.
 What is the frequency of a wave with 2.56 X 1013
meters wavelength.
 What is the energy of a wave with a wavelength of
6.45 X 10-16.

INTRO

Scientist did not believe Bohr’s model.
If the e - orbit starts to decay, the e would
be sucked into the nucleus.
Why couldn’t the electron exist in limitless
number of orbits with slightly different
energies.
ELECTRONS AS WAVES

The photoelectric effect revealed light could behave
both as a wave and a particle.

Could e - behave this way also??
ELECTRONS AS WAVES

Louis de Broglie: 1924 he hypothesized
o
De Broglie’s hypothesis: e - behave both as waves and
particles.

He felt e - should be considered waves confined to space
and that they exist in only certain frequencies.
Through experiments, e - were shown to exhibit two wavelike properties.
Two wave-like properties that strengthened de Broglie’s
hypothesis:

Diffraction: refers to the bending of a wave as it passes
by the edge of an object

Interference: overlapping of waves resulting in an
increase of energy in some areas and a decrease of
energy in other areas.
WERNER HEISENBERG

Werner Heisenberg – 1927 he was experimenting
with photons trying to detect if e - even existed.
o
Heisenberg Uncertainty Principle: states that it is
impossible to determine simultaneously both the
position and velocity of an e - (or any other particle).
ERWIN SCHRODINGER

Erwin Schrödinger: he used de Brolgie’s hypothesis
to develop a mathematical formula that treats e - as
waves.
o
Schrödinger Wave Equation – is what the formula
became known as and it, along with Heisenberg
Uncertainty Principle, laid the foundation for the
modern Quantum Theory.
SCHRODINGER’S WAVE EQUATION
QUANTUM THEORY
o
Quantum Theory: Describes mathematically the
wave properties of e - (and other particles).
The solutions (or wave functions) give only the
probability of finding an e - at a given place at a given
time.
• e - do not travel around the nucleus in neat orbits but in
regions called orbitals.
•
ORBITALS

Orbital – are three dimensional regions around the
nucleus that suggest the probable location of an e -.
ATOMIC ORBITALS & QUANTUM #S

Quantum Numbers: specify the properties of atomic
orbitals and the properties of the electrons in those
orbitals.
 There are four
numbers.
(4) quantum
1.
Principal Quantum Number (n): indicates
the energy level occupied by the electrons.



n is always a positive #; 1,2,3 etc.
More than 1 e – can exist in the same energy
level (or electron shell)
The total # of orbital in a given energy level
is equal to n2 .
2.
Angular Momentum Number (∫) – starting with
the 2nd energy level, each energy level has
different shaped orbitals called sublevels.


∫ indicates the shape of the sublevel.
The number of sublevels in each energy level
equals (n) or the number of that energy level .

Example: in the 2 energy level, there are 2
sublevels
3.
Magnetic Quantum Number (m) –
indicates the orientation of an orbital.
the s orbital is a sphere and has only one
orientation. Therefore the m valve is 0.
o # of orbitals equal n2.
o Each higher sublevel will have 2 more
orientation that the sublevel below it.
o
4.
Spin Quantum Number – electrons in an
orbital are though of as spinning on an
internal axis. It spins in one of two
directions.
o
o
an electron has only two possible fundamental
spin states in an orbital
a single orbital can hold a maximum of 2
electrons, and they must have opposite spins