Electrons In Atoms
Electrons In Atoms
Waves
1.
2.
3.
4.
Crest
Trough
Amplitude – half the height
Wavelength – distance from one point on
one wave to the same point on an adjacent
wave
5. Frequency – Number of times a wave
passes a point in one second (Hertz)
Electrons In Atoms
Waves
•
Frequency & Wavelength –
•
Frequency & Energy –
•
Wavelength & Energy –
•
Amplitude & Energy -
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•How many complete waves are shown above?
•What is the wavelength of light shown above?
Electrons In Atoms
Blu-Ray = 405 nanometers (blue light)
DVD = 650 nanometers (red light)
a. Calculate the number of
complete wavelengths
for each wave shown to
the left.
b. Calculate the
wavelength of each
wave.
c. 1 nm = 1 X 10-9 m.
Convert each
wavelength to nm.
d. Which of the waves
would be in the visible
range?
Electrons In Atoms
Light
1. All electromagnetic radiation moves at
speed of light (186,000 mi/s or 3 X 108
m/s)
2. All EM radiation is a form of light
3. Visible light = 400 nm to 700 nm
violet
red
The Electromagnetic Spectrum
Safe radiation (non-ionizing)
Radio Radar Micro
IR
Dangerous
(ionizing)
Visible
Light
UV
Light
Xrays
Gamma
Produced
by nuclear
decay
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Microwaves
Traditional Heat – increase translational
motion of water
Microwaves – increase rotational motion of
water
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Traditional Heat
Microwaves
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Light
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c = ln
c = speed of light (3 X 108 m/s)
l = wavelength (meters)
n = frequency (Hz or s-1)
Important conversion 1 nm = 1 X 10-9 m
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Calculate the wavelength of a 60 Hz EM
wave
5 X 106 m
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Calculate the wavelength of a 98.5 MHz FM
radio station
3.05 m
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Calculate the frequency of 500 nm blue light.
6 X 1014 s-1
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Light
6. Wave-Particle Duality
a. light can be viewed as both a wave and a
particle
b. Max Planck/Einstein ~1910
c. Photon – has no mass, only energy
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Light
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E = hn (for one photon)
E = Energy (J)
h = 6.63 X 10-34 J s (Planck’s constant)
n = frequency (Hz)
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Calculate the energy of laser light with a
frequency of 4.69 X 1014 s-1 .
Ans: 3.11 X 10-19 J (This is for one photon)
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Calculate the energy of a photon of wavelength
600 nm.
ANS:3.3 X 10-19 J
Electrons In Atoms
Calculate the energy of a photon of
wavelength 450 nm (blue light).
Ans: 4.42 X 10-19 J (This is for one photon)
A single photon has an energy of 3.616 X 10-19 J.
a. Calculate the frequency of the photon.
b. Calculate the wavelength of a photon in meters
c. Calculate the wavelength of a photon in
nanometers.
d. Is this photon in the visible range?
e. What range of the spectrum would you expect
a photon of 800 nm to be?
f. Calculate the energy for one mole of photons
with energy of 3.616 X 10-19 J.
a.
b.
c.
d.
e.
f.
5.45 X 1014 Hz
5.50 X 10-7 m
550 nm
Yes
IR
3.616 X 10-19 J X 6.02 X 1023 photons
1 photon
1 mole
=2.18 X 105 J/mol
Electrons In Atoms
Newtonian Mechanics
Everything is a particle
Quantum Mechanics
Everything is both a wave
and a particle
Large objects (dust, people, Photons, electrons, atoms,
baseballs, etc..)
molecules
All values are allowed
Quantized – only certain
values allowed
Predictable
Probabilistic
My l = 8.1 X 10-36 m at 3 mph
Electrons In Atoms
1. Neils Bohr Planetary Model
2. Studying line spectra of
elements
–
–
–
Only certain lines are present
(quantized)
Not a rainbow
Spectra are a fingerprint for
atoms/molecules (Astronomy)
Bohr Model
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Quantized – only certain orbits exist (rest is
forbidden zone)
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4. Ways to make something glow
Bohr Model
Photon Absorption Collision
-Glow in the dark
-Heat
-Electricity
-Chemical Reaction
Photon Absorption Collision
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Quantum Mechanical Model
Electron as a particle
Heisenberg Uncertainty
Principle – can never
know both the position
and velocity of an
electron at the same
time
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a. Electron cloud
b. Electron moves randomly (not like a planet)
c. Orbital – region of 90% probability
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nucleus
Random
electron
cloud
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Quantum Mechanical Model
Electron as Wave
Schrodinger Wave Equation
(1926) – treats electron
solely as a wave
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Quantum Mechanical Model
Result One - Explains the forbidden zone
(waves do not match)
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Quantum Mechanical Model
Waves match here
(get a clear note)
Waves do not match here
(get a bad note, forbidden zone)
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Quantum Mechanical Model
Result Two
Orbits are not circular
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Bohr Model
Explains line
spectra
Planetary model
Heisenberg
(Particle)
Schrodinger
(Wave)
Electron moves
randomly
Electron cloud
Explains f. zone
Shapes of orbits
1. Draw an s, p and d orbital
2. How many electrons can be placed in an s
orbital?
3. How many electrons can be placed in an p
orbital?
4. How many electrons can be placed in an d
orbital?
5. How many electrons can be placed in an f
orbital?
6. How did Heisenberg consider the electron?
7. How did Schrodinger consider electron?
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Quantum Numbers
First QN – how far the electron is from the
nucleus (larger the number, farther away)
– Level or shell
n=2
n=1
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Quantum Numbers
Second QN – the shape of the orbital
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Quantum Numbers
Third QN – the suborbital
Orbital
# suborbitals
Total e-
s
p
d
f
0
3 (px,py,pz)
5
7
2
6
10
14
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Quantum Mechanical Model
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Quantum Numbers
Fourth QN – spin of the electron
Pauli Exclusion Principle – two electrons in the same
suborbital (ex: px) must have opposite spins
+1/2
-1/2
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Electron
Configuration
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Electron Configurations
1. Electron Configuration – shorthand
notation to tell you the locations of all the
electrons in an atom or ion
2. Notation
2p3
Orbit
Shape
# e-
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Electron Configurations
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Electron Configurations
H
He
Li
O
Fe
S
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Electron Configurations
Be
N
Sr
P
Se
V
F
Ar
Mg
Kr
Which element is represented by the
following electron configurations?
1s22s22p63s23p64s23d5
1s22s22p63s23p64s23d104p65s24d7
1s22s22p63s23p64s1
1s22s22p63s23p3
1s22s22p63s1
1s22s22p63s23p2
1s22s22p63s23p64s23d104p6
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Noble Gas Shortcut
1. Rule – Use the noble gas in the previous row
2. Examples
Ne
P
Ru
Kr
You try:
Br Ar S
Ca
I Xe
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Exceptions
• Mostly with transition metal elements
• There is a special stability to filled and halffilled orbitals
Element Actual configuration
Cr
[Ar]4s13d5
Mo
[Kr]5s14d5
Cu
[ Ar]4s13d10
Ag
[Kr]5s14d10
Instead of
[Ar]4s23d4
[Kr]5s24d4
[Ar]4s23d9
[Kr]5s24d9
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p
Sr
+
Sr
2+
Sr
e
Ions
e- configuration
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p
S
S1S2Br1Ba2+
e
e- configuration
Ions
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Valence Electrons
1.
2.
3.
4.
Outershell Electrons
Only Electrons involved in bonding
H2O example
Many elements want 8 valence electrons
(Noble Gas Configuration)- Full Octet
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Valence Electrons
e config
H
Li
Be
Mg
#ve
Lewis dot
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Valence Electrons
e config
O
S
C
Ge
#ve
Ldot
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Valence Electrons
e config
Cl
Cl
O
1O
2O
#ve
Ldot
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Valence Electrons
e config
Na
+
Na
Mg
+
Mg
Mg+2
Ldot
e config
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B
B+1
+2
B
+3
B
Te
Te1Te2-
Ldot
Valence Electrons
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Valence Electrons
e config
Be
+
Be
Be2+
Ldot
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Gr I
Gr II
1
v. e-
2
v. e-
+1
+2
Gr III Gr IV Gr V Gr VI Gr
Gr
VII
VIII
3
4
5
6
7
8
v. e- v. e- v. e- v. e- v. e- v. e+3
No
charg
e
-3
-2
-1
0
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Periodic Properties
Periodic Properties – Properties that depend on an
element’s position on the table
Ex: Groups
H, Li, & Na all form similar oxides
(H2O, Li2O, Na2O)
Location gives you A LOT of information
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Size of Atoms
Atomic Radius
1. Measured in
picometers (1pm = 1 X 10-12 m) or
Angstroms (1 Å = 100 pm)
2. Average radius ~100 pm (1 Å)
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Size of Atoms
3. Example: Bromine
1.14 Å X 100 pm = 114 pm
1Å
1.14 Å
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Effective Nuclear Charge
Charge from nucleus that
is not blocked (shielded)
by core electrons
Zeff = Z-S
Z = # protons
S = # core electron
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What is the Zeff for Lithium (1s22s1)?
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What is the Zeff for Fluorine ([He]2s22p5)?
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e- configuration
S
O
P
O2Mg2+
K+
Zeff
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Size of Atoms
Down a group
e- config
H
Li
Na
Levels
Zeff
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Size of Atoms
Down a group – atoms get larger, more levels
e- config
H
Li
Na
Levels
Zeff
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Size of Atoms
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Size of Atoms
Across a period – atoms get smaller. Same
levels, greater Zeff (nucleus pulls electrons
closer)
Li
F
E config
levels
Zeff
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Size of Atoms
Mg
S
Sr
Electron
Config.
Levels
Zeff
a. Rank the three elements from smallest to largest
b. Which factor is most important in comparing
Mg and Sr, levels or Zeff? Explain.
c. Which factor is most important in comparing
Mg and S, levels or Zeff? Explain.
d. Which would be larger, S or S2-? Explain.
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Size of Atoms
Si
E config
levels
Zeff
Cl
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Size of Ions
A. Positive Ions
1. Example:
Mg
E config
levels
Zeff
electrons
Mg+
Mg2+
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Size of Ions
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Size of Ions
Positive ions always smaller
– Fewer electrons to control
– Less e- to e- repulsion
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Mg
E config
levels
Zeff
electrons
Mg+
Mg2+
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Size of Ions
B. Negative Ions
1. Example:
O
E config
levels
Zeff
electrons
O2-
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Size of Ions
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Size of Ions
Negative ions always larger
– More electrons to control
– More e- to e- repulsion
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More levels
If same
Greater Zeff
(same levels, greater Zeff smaller)
If same
Ions
Positive = Smaller(less electron repulsion)
Negative = Larger (more electron repulsion)
Which is larger and why?
Size Review
Li or K
S
or S2+
Mg or S
O
or Te
Which is larger and why?
Size
Review
Cl or Al
B
or B+
Al or In
B
or B-
Which is larger and why?
N or N3C or F
Sr or Be
O or O2-
Size Review
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Size Review
Kurveball
K
or K+
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Ionization Energy
A.Ionization energy – The energy needed to
remove an electron from an atom
Na  Na+ + e-
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A low energy photon will
excite an electron
A high energy photon may
ionize an atom (completely
remove the electron)
Ionization Energy (kJ/mol)
2500
He
Ne
2000
Ionization Energy (kJ/mol)
Ar
1500
H
1000
500
Li
Na
K
0
0
5
10
15
Atomic Number
20
25
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Ionization Energy
B. Across a period – Ionization Energy
INCREASES
1. Harder to remove an electron (atom is
smaller, holds e- more tightly)
2. Examples:
Li (520 kJ/mol)
F (1681)
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Ionization Energy
C. Down a group–Ionization Energy DECREASES
1. Easier to remove an electron (atom is larger,
holds e- more loosely)
2. Examples:
Li (520 kJ/mol)
Na (496 kJ/mol)
K (419 kJ/mol)
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Ionization Energy
Which has the higher Ionization Energy and why?
C or O
Na or Cl
C or Sn
Mg or Ra
Multiple Ionization Energy
Multiple Ionizations - Removing more than one
electron
1st
Mg  Mg+ + e738 kJ/mol
2nd
Mg+  Mg2+ + e1450 kJ/mol
3rd
Mg2+  Mg3+ + e- 7732 kJ/mol
There is a large jump once you reach Noble Gas
Configuration (Fewer levels, spike in Zeff)
Multiple Ionization Energy
Multiple Ionization Energy
1st
2nd
3rd
4th
Al  Al + + eAl +  Al 2+ + eAl 2+  Al 3+ + eAl3+  Al4+ + e-
577 kJ/mol
1816 kJ/mol
2744 kJ/mol
11580 kJ/mol
Multiple Ionization Energy
Examples:
a. Where will the large jump in I.E. occur for:
Be B
P
b. Element X has a large jump between its 4th
and 5th I.E. To what group does it belong?
Electrons In Atoms
Light
1. Spectroscopy
2. Spec 20
a. Light Source
b. Slit
c. Prism/Monochromator
d. Sample
e. Light Meter (PMT)
4. Excited state, can emit a photon
Electrons In Atoms
6. 2d does not exist (d’s start with 3d)
7. Area of space where an electron is likely to be
found
10.4 lobes (eggs), 4p has only 2 eggs
68. a) Tl
b) Y
c) Ce
d) As
70. 141 pm = Sn
180 pm = Tl
1.
Ba(NO3)2 In Atoms
Electrons
2. N2O4
3. Fe2(SO4)3
4. copper(II) chloride
5. nitrogren trihydride
6. Aluminum hydroxide
2Electrons
1,1
In Atoms
3 1,2
2,1
4 1,3
3,1 2,2
5 1,4
4,1 2,3 3,2
6 1,5
5,1 2,4 4,2 3,3
7 1,6
6,1 2,5 5,2 4,3 3,4
8 2,6
6,2 3,5 5,3 4,4
9 3,6
6,3 4,5 5,4
10 4,6
6,4 5,5
11 5,6
6,5
12 6,6
Answers to Review Test
1
2
3
4
5
6
7
8
9
10
C
B
A
B
A
D
B
A
C
B
11
12
13
14
15
16
17
18
19
20
D
B
A
B
D
E
D
C
B
D