Unit 5: Electrons

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Unit 5 Electrons
Our Essential Question
Where are the electrons in an atom?
X
?
The answer lies in this mystery
And so First, we must understand
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How does light travel?

• What happens when we shine a flashlight through a
  slit?

?

• What happens when we shine a flashlight through
  two slits?

Watch Dr. Quantums explanation
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Light
Youngs Double-Slit Experiment
Instructions here explanation here
Speed of light 3 x 108 m/s
1. Light travels in waves
2 really fast.
short wavelength
Swf
high frequency
long wavelength
Low frequency
Speed of light (m/s)
wavelength (m)
x frequency (1/s)
Hz
S-1
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What is the wavelength of violet light in
nanometersf 7.23 x 1014 s-1?
L2 review scientific notation Here

• Swf
• 3 x 108 m/s (w)(7.23 x 1014 s-1)
• w 3 x 108 m/s
• 7.23 x 1014 s-1
• 4.15 x 10-7 m 0.000000415 m
• 415 nm

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400-700 nm
Roy G. Biv
The Electromagnetic Spectrum
constant
often
dangerous
safe
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The story of Bohrs Epiphany
Balmer
Hydrogen
Rydberg
w(nm) 656, 486, 434, 410What number is next??
Try it for inner 2, outer 3
Show how we got 656 nm
w 656 nm
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Bohr sees the connection
Between light and the electron
X
X
Electron Emission Is Light
397
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Hydrogen Atom
5
4
-e
3 ? 2
434 nm
3
Emission
2
656 nm
-e
1
-e
1?3
P
absorption
486 nm
410 nm
-e
-e
700 nm
400 nm
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It all fits.
Bohr

• 1. Jimmy neutron no
• Shells yes
• 2. evidence emission

nucleus
2
8
18
32
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Where the electrons are exactly Aufbau order (to
Argon)
again
Aufbau order to Ar
2p6
1s2
2s2
3s2
3p6
electrons
orbitals
electrons total
shell
Config.
Nuc.
level
Paired electrons
orbital
es
1
2
3
1s2
2
s
1
2
2s2
2
s,
8
2
2p6
6
and p
2
3
3s2
s,
18
3p6
6
3p
And d
(Soon)
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Video animation 1654- 1720
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Electron Configuration of
1H
1s1
2He
3Li
1s22s1
8O
1s22s22p4
1s2
16S
1s2 2s2 2p6 3s2 3p4
Orbitals and electrons
s(2)
p(6)
d(10)
f(14)
Orbital Notation
A detailed way to show electron configuration
Orbital Notation
3Li
1s2 2s1
Electron configuration
For each orbital
electrons pair up with opposite spins
Pauli Principle
Hunds Rule
electrons spread out within orbital groups
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Orbital Notation of Carbon
6C
X
No!
Yes!
1s2
2s2
2p2
1s2
2s2
2p2
Hunds Rule Electrons spread out within orbitals
Please give the electron configuration with
orbital notation for Sulfur
16S
1s2
2s2
3s2
2p6
3p4
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Heisenbergs Uncertainty Principle

• We can never know the exact position and velocity
  of an electron at the same time.
• Why?
• (Even the smallest amount of energy moves it
  unpredictably)

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Aufbau Order
Build up
Note 4slt 3d
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Aufbau Order
He
Ne
Ar
Kr
Xe
Rn
shorthand Notation
Fill in blank table
2p6
7p6
6d10
5f14
7s2
6p6
5d10
4f14
6s2
5p6
4d10
5s2
4p6
3d10
4s2
3p6
3s2
2s2
1s2
9F
12Mg
1s22s22p63s2
1s22s22p5
Ne3s2
He2s22p5

• 1s22s22p63s23p64s23d1

• Ar4s23d1

21Sc
Kr5s24d3
1s22s22p63s23p64s23d104p65s24d3
41Nb
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Principles and rules of electron configuration
Good
Bad
Principle or rule
Heisenberg (e-position uncertain)
1s22p1
Aufbau (build up)
1s22s1
Hunds Rule (spread out)
1s2 2s2 2p2
1s2 2s2 2p2
Pauli (opp. spins)
1s2
1s2
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Valence Electrons

• Outermost shell of electrons
• Easily predictable from Periodic Table.

1
(2)
8
2
3
5
6
4
7
2
2
2
2
2
2
2
2
2
2
All 2
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Electron Dot Structures

• Quick look at valence electrons

X
Ne
Li
Be
Be
No! always spread out all 8
Try H,O,N,C
C
N
H
O
Valence electrons are the key to understanding
Chemical reactivity
Fortunately, it is nicely categorized in our next
topic
The Periodic Table
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Supplementary material
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The symmetrical periodic table that can be read
like a book.
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back
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A better periodic table?
1s (H-He)
2p (B-Ne)
2s (Li-Be)
3d (Sc-Cu)
3p (Al-Ar)
3s (Na-Mg)
4f (Ce-Lu)
4d (Y-Cd)
4p (Ga-Kr)
4s (K-Ca)
5f (Th-Lr)
5d (La)(Hf-Hg)
5p (In-Xe)
5s (Rb-Sr)
6d (Ac)(Rf-112)
6p (Tl-Rn)
6s (Cs-Ba)
7p (113-118)
7s (Fr-Ra)
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The Perfect Periodic Table
1s
2p
2s
4s
3p
3s
4d
5s
4p
3d
7s
5d
6s
5p
6p
6h
6g
6f
6d
6p
6s
7j
7i
7g
7f
7d
7p
7s
8j
8i
8h
8g
8f
8d
8p
8s
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The perfectly symmetrical periodic table.
30 es
j
i
26 es
22 es
h
g
18 es
f
14 es
d
10 es
p
6 es
s
2 es
2
3
4
5
6
7
1
8
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Light
Aristotle
Rutherford
Democritus
Dalton
Paracelsus
Thomson
Lavoisier
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Balmers Formula
Rydberg Constant
Try it for n 3
l 656 nm
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Exceptions to Aufbau Predictions(Honors Only)

• Cr
• Ar4s13d5
• Cu
• Ar4s13d10

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Summary question

• Write the
• -electron position
• -electron configuration (long)
• electron configuration (noble gas)
• And Orbital notation for Mg
• Pick a really big element- e.- config.

1s22s2 2p6 3s2
Ne3s2
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follow the periodic table
7p6
6d10
5f14
7s2
6p6
5d10
4f14
6s2
5p6
4d10
5s2
4p6
3d10
4s2
3p6
3s2
2p6
2s2
1s2
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Aufbau Order Try it
Build up
p6
s2
He
1s2
d10
Ne
2p6
2s2
1 less (3,4,5,6)
3s2
Ar
3p6
Kr
4s2
3d10
4p6
Xe
5s2
4d10
5p6
Rn
6s2
6p6
5d10
4f14
7s2
7p6
6d10
5f14
shorthand Notation
f14
2 less (4f, 5f)
7p6
6d10
5f14
7s2
6p6
5d10
4f14
6s2
5p6
4d10
5s2
4p6
3d10
4s2
3p6
3s2
2p6
2s2
1s2
9F
1s22s22p63s2
1s22s22p5
Ne3s2
He2s22p5
12Mg

• 1s22s22p63s23p64s23d1

• Ar4s23d1

21Sc
Kr5s24d3
41Nb
1s22s22p63s23p64s23d104p65s24d3
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1s2
2s2
2p6
3s2
4s2
5s2
4d10
4f14
2p6
2p6
3p6
4p6
5d10
3d10
7p6
6d10
5f14
7s2
6p6
5d10
4f14
6s2
5p6
4d10
5s2
4p6
3d10
4s2
3p6
3s2
2p6
2s2
1s2
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Insert the aufbau order 1s2 2s2 2p6 2s2 2p6 4s2
3d10 etc To show the infinite pattern without The
diagonal line pattern
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The questions I cannot answer

• Electron emission is light. Is emission only for
  n values, meaning for ex 3rd shell to 2nd shell,
  or is it for subshells, like p to s?
• Arent the inner shells already full?
• The p orbitalthe s orbitalwhat about the
  nucleus- isnt it in the way?
• Whats the diffference between electron
  absorption and ionizationdoes it go out 5
  shells, and then just fall off?