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Modern ChemistryChapter 4
Arrangement of Electrons
in AtomsSections 1-3
The Development of a New Atomic ModelThe Quantum Model of the Atom
Electron Configurations
Chapter 4 Section 1 New Atomic Model pages 97-103
2
Section 1
The Development of a New Atomic
Model
Chapter 4 Section 1 New Atomic Model pages 97-103
3
Sect
ion 1
Voca
bula
ry Electromagnetic radiationElectromagnetic spectrumWavelengthFrequencyPhotoelectric effectQuantumPhotonGround StateExcited stateLine-emission spectrumContinuous spectrum
Chapter 4 Section 1 New Atomic Model pages 97-103
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Properties of Light• Electromagnetic Radiation: a form
of energy that exhibits wavelike behavior as it travels through space.
• Wavelength: the distance between corresponding points on adjacent waves
• Frequency: the number of waves that pass a given point in a specific time.
Chapter 4 Section 1 New Atomic Model pages 97-103
5
Wavele
ngth
an
d F
requ
en
cy Im
ag
e
p. 9
8
Chapter 4 Section 1 New Atomic Model pages 97-103
6
Electromagnetic Spectrum Image
p. 9
8
Chapter 4 Section 1 New Atomic Model pages 97-103
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Ele
ctro
mag
neti
c S
pect
rum
Im
ag
e
p. 9
8
Chapter 4 Section 1 New Atomic Model pages 97-103
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Properties of Light• wavelength x frequency = speed of light
• x = c• Visible Light = R O Y G B I V
Long
Low Low E
Short
High High E
Chapter 4 Section 1 New Atomic Model pages 97-103
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The Photoelectric Effect • Max Planck proposed that energy is
proportional to the frequency of the electromagnetic wave.
• Electromagnetic energy is emitted from objects in small packages called quanta.
• E = h •Planck’s constant
–h = 6.626 x 10-34 J•sec
Chapter 4 Section 1 New Atomic Model pages 97-103
10
Quanit
izati
on o
f En
erg
y
Anim
ati
on
Chapter 4 Section 1 New Atomic Model pages 97-103
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The Photoelectric Effect • Albert Einstein expanded on
Planck’s idea.• Electromagnetic radiation has a
dual wave-particle nature.• A particle of light is a photon.• Photon: a particle of
electromagnetic radiation having zero mass and carrying a quantum of energy.
• Ephoton = h
Chapter 4 Section 1 New Atomic Model pages 97-103
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En
erg
y o
f a P
hoto
n A
nim
ati
on
p. 9
8
Chapter 4 Section 1 New Atomic Model pages 97-103
13
The Photoelectric Effect• The
photoelectric effect refers to the emission of electrons from a metal when light shines on the metal.
p. 9
9
Chapter 4 Section 1 New Atomic Model pages 97-103
14
Photo
ele
ctri
c E
ffect
An
imait
on
Chapter 4 Section 1 New Atomic Model pages 97-103
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The Photoelectric Effect To knock an electron loose,it must be hit with a photon whichpossesses a minimum amount of energy.This energy corresponds to its frequency.Different metals hold electrons
more or less tightlySo different metals require
different frequencies to show the photoelectric effect.
Chapter 4 Section 1 New Atomic Model pages 97-103
16
The H-Atom’s Line Emission Spectrum
• Electric current is passed through a vacuum tube with hydrogen in it.
• A glow is produced• When shined
through a prism a line emission spectrum is produced
p. 1
01
Chapter 4 Section 1 New Atomic Model pages 97-103
17
Hydrogen’s Line Emission Spectrum
Insert Glencoe Disk 1
Chapter 4 Section 1 New Atomic Model pages 97-103
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Abso
rpti
on a
nd
Em
issi
on
S
pect
rum
An
imati
on
Chapter 4 Section 1 New Atomic Model pages 97-103
19
Line Emission SpectrumInsert Glencoe Disk 1
Chapter 4 Section 1 New Atomic Model pages 97-103
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Bohr Model of the Atom • Niels Bohr proposed orbits for the
electrons• Each orbit has a fixed energy• Lower energy orbits are closer to
the nucleus• Between orbits the
electron cannot exist
Chapter 4 Section 1 New Atomic Model pages 97-103
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Explaining the Line Emission Spectrum An electron absorbs a specific amount of
energy (absorption) and moves from its ground state to an excited state
Chapter 4 Section 1 New Atomic Model pages 97-103
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Explaining the Line Emission Spectrum The electron returns to its ground
state and emits a photon (emission).
Chapter 4 Section 1 New Atomic Model pages 97-103
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Explaining the Line Emission Spectrum This photon has an energy corresponding to
the difference between the two states.This photon has a specific E, , and color.
Chapter 4 Section 1 New Atomic Model pages 97-103
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Photo
n E
mis
sion
and
Ab
sorp
tion
Im
ag
e
p. 1
02
Chapter 4 Section 1 New Atomic Model pages 97-103
25
Bohr Model of the Atom • Bohr’s calculated values for the
lines agreed with the values observed for the lines in each series.
• However, it did not explain the spectraof atoms with more thanone electron.
Chapter 4 Section 1 New Atomic Model pages 97-103
26
Bohr
Mod
el of
the A
tom
A
nim
ati
on
Chapter 4 Section 1 New Atomic Model pages 97-103
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Bohr and Einstein
Chapter 4 Section 1 New Atomic Model pages 97-103
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Section 1 Homework
