CHEMISTRY
Part One
Quantum Mechanics
and
Atomic Structure
Electromagnetic Radiation
• Electromagnetic Radiation is radiant energy that
travels in waves in both the electric and magnetic
realms.
What are EM Rays?
• The Spectrum of light gives us the clue.
All visible light can be
separated into a
spectrum of colors by
using a prism.
The Electromagnetic Spectrum
• White light passing through a prism
White Light
Red Light
Orange Light
Yellow Light
Green Light
Blue Light
Violet light
At The End of The Rainbow
Violet Light
• When white light passes
Indigo Light
• Through a prism
Blue Light
Green Light
White Light Yellow Light
Prism Orange Light
Red Light
ROY G BIV
A View from the Top
Top View
White Light
beam Narrow White
Light beam
Slit
Prism
Light Source
Photographic film
Enclosed in a black box
Light is Energy that Travels in
Waves
As a light wave travels through a prism it collides
with the molecules of the prism and is bent.
λ = Greek letter “ Lambda “ for wavelength
Let’s Shed a Little Light on the Subject
• Spectrum of Energy : The colors of the
Rainbow all have different wavelengths
Waves
• Electromagnetic Spectrum
λ
The colors in
white light have
different If we count
wavelengths and the number
that is why they of peaks
can be separated that pass by
in a prism. when the
wave travels
this is called
frequency.
Represented
by the Greek
λ = Greek letter “ Lambda “ for wavelength letter “џ”
Is Light the Only Path?
• Visible light is not the only form of
electromagnetic radiation ( EMR ).
Increasing frequency
Radio Micro Infrared Visible Ultra X-Ray Gamma
Violet
Increasing Wavelength
Proposition
• If the atom can be excited to produce EMR
then we can measure the wavelengths and
determine something about the energy
levels of the atom.
• Lets look at what we know about waves.
Wavelength
Transitional velocity = speed of light ( EMR )
Math Relationship
• The frequency and wavelength are inversely
proportional.
ν = c/λ
λ = c/ν
ν is the Greek letter “ nu “ which is used for frequency
c the velocity of EMR or the speed of light = constant
c = 3.00 x 108 m/s or 3.00 x 1017 nm/s
Lets Measure the Wavelength
• If we pass an electric current through a
gas the electrons absorb the energy and
then tend to reach a lower energy state by
releasing that energy in the form of EMR.
E- Tends to lower energy
EMR
Higher State We can measure wavelength
energy
E- E-
Laboratory
Experiment on wavelength
Meter stick to
measure wavelength
Cathode ray tube
filled with H2
<-Electric current
Colored light
Power Source
Diffraction gradient
A Little View
• Diagram: Lets take it from the top
Diffraction Gradient
λ
Direction of wave
Wave (Top View) As the waves pass through the
DG they break up and are
reinforce to show the color.
A Little Trig
• Diagram ● 1st Spectral Line
● Y = distance to 1st line
d = distance on DG
‹
Eye ● ۞ Light Source
L = distance
observer from
source
Diffraction Gradient
λ = yd
L
Does this add up?
• Calculations: The diffraction gradient has 13,100
lines per inch. 1.00 in = 2.54 cm
• 2.54 cm = 1.94 x 10-4cm
• 13,100 lines line
Therefore d = 1.94 x 10-4cm
L = the distance the observer stands from the source.
we will stand 100 cm; Therefore L = 100 cm
λ = yd y (1.94 x 10-4cm) x 1.00 x 107 nm = 19.4 y nm
L 100 cm cm cm
Calculations
Meter Stick
• Diagram ● _ 1st color = Red
_
● _ Y = 32 cm
‹
_
Eye ● ۞_ Light Source
L = 100 cm _
Diffraction Gradient λ = 19.4 y nm/cm
= 19.4 nm x 32 cm
cm
= 621 nm
So What!
• What about the frequency?
• v= c/λ c = velocity of EMR = 3.00 x 1017nm/s
• = 3.00 x 10 17nm/s
• 621 nm
• = 4.83 x 1014 1/s ( s-1) or hertz (Hz)
• cycles per second
Energy
• It can be demonstrated that Energy due to a
wave of radiant energy is inversely proportional
to the wavelength
• E = hc/λ
• h=Planck’s constant = 4.00 x10-10 js
• c=velocity of EMR = 3.00 x 1017 nm/s
• Since h and c are constants we can simplify
• E = (4.00 x10-10 js)(3.00 x 1017nm/s) x 1.00 kj/j=1.20 x 105 kj nm
• λ λ
Continue
• If I measured a wavelength of orange to be 30.0
cm on the metric ruler then the energy could be
calculated:
• E = 1.20 x 105 kj nm
• λ
• =1.20 x 105 kj nm
• 19.4 nm/cm ( 30.0 cm )
• = 206 kj
Remember This?
• Visible light is not the only form of
electromagnetic radiation ( EMR ).
Increasing frequency
Radio Micro Infrared Visible Ultra X-Ray Gamma
Violet
Increasing Wavelength
Let’s Stand up
• Lets Graphically represent the energy levels
in waves of Light
E4
E3
Increasing
Energy
E2
E1
Quantum Mechanics
• In studying electron structure we must
consider 4 parameters of position.
• Energy
• Probability
• Orientation in space
• Movement of electrons
We Know about energy of
electrons
We measure the Energy by measuring wavelength
Meter stick to
measure wavelength
Cathode ray tube
filled with H2
<-Electric current
Colored light
Power Source
Diffraction gradient
Shocking
• If we pass an electric current through a
pure gas the electrons absorb the energy
and then tend to reach a lower energy
state by releasing that energy in the form
of EMR.
E- Tends to lower energy
EMR
Higher State We can measure wavelength
energy
E- E-
Spectrum
• Since the spectrum we get is a bright line
spectrum we know that the electrons exist
in a definite energy level as opposed to a
continuous flow of levels.
What is the difference?
• Compare
Continuous Spectrum
Would indicate a
continuous number of
energy levels.
A bright line Spectrum
Would indicate a
definite number of
energy levels.
Its All About the Energy
• Since experiments show that the electrons in an
atom produce a bright line spectrum, then we can
conclude that they exist in DEFINITE energy
levels in stead of a continuous set of energy
levels.
n = 4 – 4th energy level
The symbol for the energy
n = 3 – 3rd energy level level is “ n “
E-
n = 2 – 2nd energy level Energy of only
one wavelength
E-
n = 1 – 1st energy level
Energy put into the
system
First
• The first parameter is that all electrons exist in
different but definite energy levels.
• The first quantum number is represented by the
letter “ n “.
• n = 1, 2, 3, 4, 5 ● ● ● ● ● Infinity
Second
• The second parameter for understanding the
position of the electron in respect to the nucleus is
its probable location. Using complicated quantum
mechanical equations a pattern of possible positions
is plotted on a graph.
The shape of
the 1st energy
is spherical
and is called a
1s orbital
Movin on Up
• As the energy increases the probability of
different patterns and shape increases.
• Consider when n = 2.
Two different shapes emerge
with distinct properties.
P Orbital
• The p orbital is manifested in 3 planes.
• These shapes only begin when n = 2.
• The higher the energy, the greater
probability of position for an electron.
The “d’s”
• The d Orbitals are in 5 geometric spaces
• They only begin when n = 3
2 Down and 2 to Go
• So far we have discussed 2 of 4 parameters,
energy and shape of probable position.
• n = energy level with values from 1 to infinity
• The letter used to designate the orbital quantum
number is “ l “.
• l = 0, 1, 2, ● ● ● ● n-1
• The next parameter is the electron’s orientation in
space.
Orientation
We locate Orbitals with an x, y, and z axis
py
px
x
The p-orbital is
z located along and
pz x,y,z plane.
y
Quantum Values
• The orientation in space is referred to as the
magnetic quantum number.
• The values of this are determined by the l
quantum number.
• ml = -l…0…+ l
• If l = 0 then ml = 0, If l = 1 then ml = -1,0,1
Lets Put a Spin on It
• The Final parameter we need to discuss is
what the electron is doing.
• The electron is not stagnate but we know
from experiments it is spinning.
The symbol for The values for
the spin QN is E-
ms are ± 1/2
for each ml
ms
All together now!
Name of Symbol of Denotes Allowed
QN QN Values
Principal n Energy Level N = 1,2,3…Inf
QN
Orbital l Shape of l= 0,1,..n-1
QN orbital
Magnetic ml Orientation in ml =- l ..0.. +l
QN space (# geometric spaces)
Spin ms Spin of the ms = ± ½
QN electron
Allowed Values
ECN
1s2 2s2 2p6 3s23p63d10
n 1 2 2 4
3
l 0 0 1 0 1 2 ?
ml
-2
-1
0 0 -1,0,1
-1
0
0 0
1
?
1 2
ms
±1/2 ±1/2 ±1/2/ml ±1/2 ±1/2 ±1/2
?
Let’s Get Graphic
Sub Level
• Energy Diagram: 4f14
4d10
Energy Level
4p6
n=4
3d10
4s2
n=3 3p6
3s2
2p6
n=2
Energy
2s2
n=1
1s2
Sequence
• We would expect that the sequence of orbital
filling would be in order, however nature doesn’t
follow our logic but has its own. There are
explanations for these variations which at closer
inspection make sense.
We sit at the
• THE ORDER Periodic Table
• 1s
• 2s 2p
• 3s 3p
• 4s 3d 4p
• 5s 4d 5p
• 6s 4f 5d 6p
• 7s 5f 6d 7p
And the Order is
• The Periodic Table
S1 p6
1 S2
p1 p2 p3 p4 p
5
2
3 The “d’s”
4
5
6
7
The “f’s”
Atomic Structure
• Electron Configuration Notation (ECN )
Atomic # Symbol ECN
1 H 1S1
2 He 1S2
3 Li 1S22s1
4 Be 1S22s2
5 B 1S22s22p1
And Sole On
• Continue with ECN
Atomic # Symbol ECN
6 C 1S22s22p2
7 N
1S22s22p3
8 O 1S22s22p4
9 F
1S22s22p5
10 Ne
1S22s22p6
Let’s Get to the Core
• The ECN Core Method
• Since the next element in our series is Element # 11,
Na it would have the following ECN
• 1s22s22p63s1 [1020Ne]3s1
This is the Core method
=
Every element in the 3rd
This is the structure of Ne row will have the same
core
Down to the Core
• Continue with Core ECN
Atomic # Symbol ECN
11 Na [1020Ne] 3S1
12 Mg [1020Ne] 3S2
13 Al [1020Ne] 3S23p1
14 Si
“ 3S23p2
15 P
“ 3S23p3
Another Method?
• In order to understand exactly what the structure
of an atom is, sometimes we have to approach it
another way.
• ELECTRON ORBITAL NOTATION ( EON )
• When representing Orbitals and electrons in the
Orbitals we use brackets or circles for the
Orbitals and arrows or lines to represent the
electrons.
• [ ] Ο
E- E-
The up and down arrows indicate The right and left lines indicate
opposite spins opposite spins
Series Four
• A “d” transition
Atomic # Symbol EON
19 K [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
20 Ca [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
21 Sc [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
22 Ti [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
Continue
• A “d” transition
Atomic # Symbol EON
23 V [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
24 Cr [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
24 Cr [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
Hund’s Rule: There is a stability
associated with a ½ filled or
filled d orbital.
Continue
• A “d” transition
Atomic # Symbol EON
25 Mn [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
26 Fe [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
27 Co [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
28 Ni [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
Continue Law: There is a stability
Hund’s
associated with a ½ filled or filled
d orbital
• A “d” transition
Atomic # Symbol EON
29 Cu [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
30 Zn [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
31 Ga [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
32 Ge [1840Ar] 4s 3d 4p
Ο ΟΟΟΟΟ ΟΟΟ
What about the “F,s”
• The is a similar transition occurring in the f-series
electrons. The order of filling varies from the
expected order but in a different way from the d-
series. In order to explain what happens in nature we
have to pay attention the periodic table and the
position of the elements.
• We will investigate this starting with the 6th series
and element number 55 Cs.
• We will use the ECN to explain this transition.
F-Transitions
Atomic # Symbol ECN
55 Cs [54131Xe] 6s1
56 Ba [54131Xe] 6s2
57 La [54131Xe] 6s25d1
58 Ce [54131Xe] 6s25d14f1
59 Pr [54131Xe] 6s24f3
60 Nd [54131Xe] 6s24f4
61 Pm [54131Xe] 6s24f5
F-Transitions
Atomic # Symbol ECN
62 Sm [54131Xe] 6s24f6
63 Eu [54131Xe] 6s24f7
64 Gd [54131Xe] 6s24f75d1
65 Tb [54131Xe] 6s24f9
66 Dy [54131Xe] 6s24f10
67 Ho [54131Xe] 6s24f11
68 Er [54131Xe] 6s24f12
F-Transitions
Atomic # Symbol ECN
69 Tm [54131Xe] 6s24f13
70 Yb [54131Xe] 6s24f14
71 Lu [54131Xe] 6s24f145d1
72 Hf [54131Xe] 6s24f145d2
73 Ta [54131Xe] 6s24f145d3
74 W [54131Xe] 6s14f145d5
75 Re [54131Xe] 6s24f145d5
DOT DOT DOT
• Another way to represent atomic Structure is The
Electron Dot Notation EDN.
• The EDN only shows the outer orbital electrons.
• What is the highest energy level in the structure
of Dy ?
[54131Xe] 6s24f10
The answer is not
6 is the highest energy level and 10
the EDN only shows those 2
electrons because they are the Not 12
ones involved in forming But 2
compounds.
How About This
• How many electrons in the outer orbital for
• GROUP 1 1
2 Who is buried
• GROUP 2
in Grant’s
Tomb?
• GROUP 3 3
• GROUP 5 5
• GROUP 7 7
Let’s Do This
• Any Chemical Symbol The Position of
Electrons around a
Px electrons symbol are as
3 6 follows:
7
Py electrons
4S8 5
2 s electrons
1
Pz electrons
EDN
• Draw the EDN for the following:
• # 19 K Group 1 1 electron K●
Sr●
• # 38 Sr Group 2 2 electrons ●
●
• # 31 Ga Group 3 3 electrons Ga●
●
● ●
• # 14 Si Group 4 4 electrons ● Si●
● ●
• # 33 As Group 5 5 electrons ●As●
●
●
●●
• # 16 S Group 6 6 electrons ●●S●
MORE EDN
• Continue
• # 18 Ar Group 8 8 electron ●● ●
Ar ●
●● ●●
• # 47 Ag Trans 1 electrons Ag●
s1d5
• # 44 Ru Trans 2 electrons Ru●
●
• # 62 Sm
●
Rare 2 electrons Sm●
Practice
• Draw The ECN, EON, and EDN for # 83 Bi
Use the Core Method
p3
And Triangulate Position
The
131Xe
54 Core
Period 6 Bi
The last
orbital to
fill 6p3
Ready, Set, Go
• # 83 Bi
• ECN [54131Xe] 6s2 4f14 5d10 6p3
• EON [54131Xe] 6s 4f 5d 6p
• O OOOOOOO OOOOO OOO
• EDN Bi is in Group V
●●
• ● Bi ●
●