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Chapter 5
Electrons in Atoms
Nice!!
Dalton
1803
That’s
Cool!!
J.J. Thompson
1897
Rutherford
1911
I’m the
Man!!
Niels Henrik David Bohr
1885 - 1962
Bohr’s Model of the Atom
1913
Quantum Model
nucleus
+
electron
-
Quantum Model
ENERGY
-
+
+
Quantum Model
-
Quantum Model
+ -
Quantum Mechanical Model
The Quantum Mechanical
Model determines the
allowed energy an electron
can have and how likely it
is to find the electron in
various locations around
the nucleus.
Atomic Orbital
An Atomic Orbital is a
region of space in
which there is a high
probability of finding
an electron.
S - orbital
px - orbital
py - orbital
pz - orbital
d - orbital
Principal Number
Type of
Energy
of
Sublevel
Levels Sublevels
n=1
1
1s
n=2
2
2s, 2p
n=3
3
n=4
4
3s, 3p,
3d
4s, 4p,
4d, 4f
Maximum Number of Electrons
Energy
Level (n)
Maximum
Electron
1
2
3
4
2
8
18
32
Homework
Section: 5-1
Practice Problems
Review
Due: 10/25/05
Electron Arrangement
in Atoms
Electron Configurations
Aufbau Principle
Pauli Exclusion Principle
Hund’s Rule
Aufbau Principle
1s
Orbital
Aufbau Principle
2px 2py 2pz
Orbitals
5s
4s
3s
2s
1s
4p
3d
3p
2p
Pauli Exclusion Principle
s - orbital
- electron
2 electrons
per orbital
- direction of spin
Hund’s Rule
2px 2py 2px
Same Energy Same Spin in Each
Match with Opposite Spin
Orbital Filling
Elem.
H
1s 2s 2px 2py 2pz
Electron
Config.
He
1s1
1s2
Li
1s22s1
C
1s22s22p2
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 2 electrons
2
• 1s
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 4 electrons
2
2
• 1s 2s
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 12 electrons
2
2
2
6
• 1s 2s 3s 3p
The easy way to remember
7s 7p 7d 7f
• 14 electrons
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
2
2
2
6
2
• 1s 2s 3s 3p 4s
1s
The easy way to remember
7s 7p 7d 7f
• 38 electrons
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2
2
2
6
2
2s 2p
• 1s 2s 3s 3p 4s
10
6
2
3d 4p 5s
1s
The easy way to remember
• 38 electrons
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
2
2
2
6
2
3s 3p 3d • 1s 2s 3s 3p 4s
10
6
2
10
3d 4p 5s 4d
2s 2p
6
2
5p 6s
1s
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 88 electrons
2
2
2
6
2
• 1s 2s 3s 3p 4s
10
6
2
10
3d 4p 5s 4d
6
2
14
10
5p 6s 4f 5d
6
2
6p 7s
The easy way to remember
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
• 108 electrons
2
2
2
6
2
• 1s 2s 3s 3p 4s
10
6
2
10
3d 4p 5s 4d
6
2
14
10
5p 6s 4f 5d
6
2
14
10
6p 7s 5f 6d
6
7p
Exceptional
Electron Configurations
Orbitals fill in order
Lowest energy to higher
energy.
Adding electrons can change
the energy of the orbital.
Half filled orbitals have a
lower energy.
Makes them more stable.
Changes the filling order
Write these electron
configurations.
Titanium - 22 electrons
– 1s22s22p63s23p64s23d2
Vanadium - 23 electrons
– 1s22s22p63s23p64s23d3
Chromium - 24 electrons
– 1s22s22p63s23p64s23d4 expected
– But this is wrong!!
Write these electron
configurations.
Titanium - 22 electrons
– 1s22s22p63s23p64s23d2
Vanadium - 23 electrons
– 1s22s22p63s23p64s23d3
Chromium - 24 electrons
– 1s22s22p63s23p64s23d4 expected
– But this is wrong!!
Write these electron
configurations.
Titanium - 22 electrons
–1s22s22p63s23p64s23d2
Vanadium - 23 electrons
–1s22s22p63s23p64s23d3
Chromium - 24 electrons
–1s22s22p63s23p64s23d4
Right? No, wrong!!
Chromium is actually:
1s22s22p63s23p64s13d5
Why?
Slightly lower in energy.
The same principal
applies to copper.
Copper’s electron
configuration
Copper has 29 electrons
1s22s22p63s23p64s23d9
Actual Configuration is:
2
2
6
2
6
1
10
1s 2s 2p 3s 3p 4s 3d
Lower Energy
Light
The study of light led to the
development of the quantum
mechanical model.
Light is a kind of
electromagnetic radiation.
Electromagnetic radiation
includes many kinds of waves
8
All move at 3.00 x 10 m/s = c
Parts of a wave
Crest
Wavelength λ
Amplitude
Origin
Trough
Parts of Wave
Origin - the base line of the
energy.
Crest - high point on a wave
Trough - Low point on a wave
Amplitude - distance from
origin to crest
Wavelength - distance from
crest to crest
Frequency
The number of waves that
pass a given point per second.
Units: cycles/sec or hertz (hz
or sec-1)
Abbreviated by Greek letter
nu = n
c = ln
Frequency and wavelength
Are inversely related
As one goes up the other goes
down.
Different frequencies of light are
different colors of light.
There is a wide variety of
frequencies
The whole range is called a
spectrum.
Low
energy
Electromagnetic
Spectrum
High
energy
Radio Micro Infrared
Ultra- XGamma
waves waves .
violet Rays Rays
Low
High
Frequency
Frequency
Long
Short
Wavelength
Wavelength
Visible Light
ROYGBIV
Homework
Page: 140
Problems: 14, 15
Due: 11/8/04
Prism
White light is
made up of all the
colors of the
visible spectrum.
Passing it through
a prism separates
it.
If the light is not white
By heating a gas
with electricity we
can get it to give
off colors.
Passing this light
through a prism
does something
different.
Atomic Spectrum
Each element
gives off its own
characteristic
colors.
Can be used to
identify the atom.
How we know
what stars are
made of.
• These are called
discontinuous
spectra, or line
spectra
• unique to each
element.
• These are emission
spectra.
• The light is emitted
given off.
Changing the energy
Let’s look at a hydrogen atom
Changing the energy
Heat or electricity or light can
move the electron up energy
levels (“excited”)
Changing the energy
As the electron falls back to
ground state, it gives the
energy back as light
Changing the energy
May fall down in steps
Each with a different energy
Ultraviolet
Visible
Infrared
Further they fall, more
energy, higher frequency.
the orbitals also have
different energies inside
energy levels
All the electrons can move
around.
What is light?
Light is a particle - it
comes in chunks.
Light is a wave- we can
measure its wavelength
and it behaves as a wave
c=ln
E = hn
Energy
E = hn
Energy
Constant
h = 6.626 X
Frequency
-34
10
J•s
Heisenberg Uncertainty
Principle
It is impossible to know exactly
the location and velocity of a
particle.
The better we know one, the less
we know the other.
Measuring changes the
properties.
Instead, analyze interactions
with other particles
The physics of the very small
Quantum mechanics explains
how the very small behaves.
Classic physics is what you get
when you add up the effects of
millions of packages.
Quantum mechanics is based on
probability
Heisenberg Uncertainty Principle
It is impossible to know exactly
the location and velocity of a
particle.
The better we know one, the less
we know the other.
Measuring changes the
properties.
Instead, analyze interactions with
other particles
Before
Photon
Moving
Electron
After
Photon
changes
wavelength
Electron
Changes velocity
Homework
Practice Problems
5-1 Review
Due: 11/9/04
Test: 11/16/04
Homework
5-2, 5-3 Review
Due: 11/12/04
Test: 11/16/04