Transcript hchem_ch4-1 - Mrs. G Chemistry 2015-2016

Modern Chemistry
Chapter 4
Arrangement of Electrons
in Atoms
Sections 1-3
The Development of a New Atomic Model
The Quantum Model of the Atom
Electron Configurations
1
Section 1
The Development of
a New Atomic Model
Chapter 4 Section 1 New Atomic
Model pages 97-103
2
Section 1 Vocabulary
Electromagnetic radiation
Electromagnetic spectrum
Wavelength
Frequency
Photoelectric effect
Quantum
Photon
Ground State
Excited state
Line-emission spectrum
Continuous spectrum
Chapter 4 Section 1 New Atomic
Model pages 97-103
3
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
4
Wavelength and Frequency
Image
p. 98
Chapter 4 Section 1 New Atomic
Model pages 97-103
5
p. 98
Electromagnetic Spectrum Image
Chapter 4 Section 1 New Atomic
Model pages 97-103
6
Electromagnetic Spectrum Image
p. 98
Chapter 4 Section 1 New Atomic
Model pages 97-103
7
Properties of Light
• wavelength x frequency = speed of light
•

x

=
• Visible Light = R O Y G B I V
Long 
Low 
Low E
c
Short 
High 
High E
Chapter 4 Section 1 New Atomic
Model pages 97-103
8
The Photoelectric Effect
p. 99
• The photoelectric
effect refers to
the emission of
electrons from a
metal when light
shines on the
metal.
Chapter 4 Section 1 New Atomic
Model pages 97-103
9
Photoelectric Effect Animaiton
Chapter 4 Section 1 New Atomic
Model pages 97-103
10
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
11
Quanitization of Energy
Animation
Chapter 4 Section 1 New Atomic
Model pages 97-103
12
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
13
Energy of a Photon Animation
p. 98
Chapter 4 Section 1 New Atomic
Model pages 97-103
14
The Photoelectric Effect
To knock an electron loose,
it must be hit with a photon which
possesses a minimum amount of energy.
This energy corresponds to its frequency.
Different metals hold electrons
more or less tightly
So different metals require
different frequencies to
show the photoelectric
effect.
Chapter 4 Section 1 New Atomic
Model pages 97-103
15
The H-Atom’s Line Emission Spectrum
p. 101
• 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
Chapter 4 Section 1 New Atomic
Model pages 97-103
16
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
20
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
21
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
22
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
23
Photon Emission and Absorption
Image
p. 102
Chapter 4 Section 1 New Atomic
Model pages 97-103
24
Bohr Model of the Atom
Animation
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 spectra
of atoms with more than
one electron.
Chapter 4 Section 1 New Atomic
Model pages 97-103
26
Bohr and Einstein
Chapter 4 Section 1 New Atomic
Model pages 97-103
27
Section 1 Homework
Chapter 4 Section 1 New Atomic
Model pages 97-103
28