Download Quantum Mechanical Model

Can only refer to the probability of finding
an electron in a region; cannot specify path
1.
a.
b.
Heisenberg Uncertainty Principle-impossible to
determine simultaneously both position and
velocity of any particle (electron) at same
time.
Orbital- 3 dimensional electron density mapprobability (electron cloud)-firefly analogy
The kinetic energy of the electron in an
atom is inversely related to volume.
2.
a.
b.
3.
Explains the stability of an atom
As electrons move closer to the nucleus, the
energy (kinetic) increases.
Four quantum numbers are required to
describe completely the energy of an
electron in an atom.
Principle quantum number (n)
1.
a.
b.
Main energy level occupied by electron
Positive integers 1, 2, 3, ….
b. n = 1, 2,3-the value of n is the main factor
that determines the energy of an electron
and its distance from the nucleus.
n
n
n
n
=
=
=
=
1
2
3
4
c. As n increases
a.
Orbital larger
b.
Electrons further from nucleus
Maximum capacity of principal energy level is
2n2
n
1
2
3
4
Max
number
of e-
2
8
18
32
Angular momentum quantum number (ℓ)
2.
Shape of atomic orbital
a.
a.
b.
c.
d.
S orbitals – spherical
P orbitals – dumbbell shape
D orbitals – more complex
F orbitals – even more complex
(0)
(1)
(2)
(3)
s orbitals
p orbitals
d orbitals
s orbitals
p orbitals
d orbitals
No.
orbs.
1
3
5
No.
e-
2
6
10

Indicate by a superscript the number of
electrons in each sublevel.
H-1s1
 He-1s2
 Li-1s2 2s1

Super scripts should add up to the atomic #
which is the number of electrons an atom has.
 Noble gas electron configuration (short hand)Use the noble gas from the end of the previous
row or period and put in brackets. Start
electron configuration from there.


Li-[He] 2s1
 Groups
1 and 2: Fill the s sublevel
 Groups 13-18:
Fill the p sublevel
 Groups 3-12:
Fill the d sublevel
 Lanthanide and Actinides:
Fill the 4f and 5f sublevels
Magnetic quantum number (mℓ)
3.
a.
Indicates orientation of orbital around nucleus
mℓ = -ℓ, …, -1, 0, 1, …, ℓ
Spin quantum number (ms)
4.
a.
b.
Spin status
Clockwise or counterclockwise
1.
2.
No two electrons in an atom can have the
same set of four quantum numbers
This means that only 2 electrons can fit
into an orbital-must have opposite spins
1.
2.
Electron configuration
Aufbau Principle-an electron occupies the
lowest energy orbital that can receive it.
Electrons are added one by one
3.
Orbital diagrams-diagram of electrons
Hund’s Rule
-orbitals of equal energy are each occupied by one
electron before any orbital is occupied by a
second electron AND
-all electrons in singularly occupied orbitals must
have the same spin
 Ground
state-all electrons are in the lowest
possible energy levels.
 When
an atom absorbs energy, it can move to
a higher energy level or excited state.
A
photon is given off when an excited
electron drops down to the ground state as
energy is released.
 Carbon


Ground state-1s22s22p2
Excited state-1s22s12p3

An electron from the 2s orbital has absorbed energy
and moved to the 2p orbital