Transcript Chapter 20 Oxidation-Reduction Reactions

Chemistry Warm Up
Some Dimensional Analysis Review.
PLEASE SHOW YOUR WORK USING CONVERSION
FACTORS AND DIMENSIONAL ANALYSIS
1. If 6.02 x 1023 atoms of carbon have a mass of 12.0 grams,
what the mass of 1.51 x 1023 atoms of carbon atoms. Hint:
set up the equality that you know. Make two conversion factors and
use one to solve the problem. Check your work using dimensional analysis.
2. How many atoms are there in sample of carbon that weighs
30.0grams?
3. How many atoms are there in a sample that weighs 3.60 x
102 grams?
Chemistry Warm Up: Periodic Table Scavenger Hunt
1. The periodic table is arranged by atomic number,
not by atomic mass. Find a sequence of three
elements that are arranged by atomic number but
not by atomic mass.
2. Find three elements whose symbols don’t seem to
have anything to do with their names. Write the
name and the symbol for each.
3. There are two rows at the bottom of the periodic
table. Use the atomic number to figure out where
they fit in to the periodic table.
4. What would the periodic table look like if those two
rows were inserted in order of their atomic number?
Make a sketch.
Chapter5.1 Models of the Atom
California State Science Standards Chemistry
1. The periodic table displays the elements in increasing
atomic number and shows how periodicity of the physical and
chemical properties of the elements relates to atomic structure.
As a basis for understanding this concept:
g.* Students know how to relate the position of an element in
the periodic table to its quantum electron configuration and to
its reactivity with other elements in the table.
i.* Students know the experimental basis for the development
of the quantum theory of atomic structure and the historical
importance of the Bohr model of the atom.
Chapter5.1 Models of the Atom
Dalton- Indivisible Atom
J.J.Thomson
discovers subatomic
particle
“Plum pudding,”
model
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Development of Atomic Models
Rutherford’s Model
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Dense central Nucleus
Electrons orbit like planets
Atom mostly empty space
Does not explain chemical
behavior of atoms
The Bohr Model
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Electrons orbit the nucleus
Specific circular orbits
Quantum =
energy to move
from one level
to another
The Bohr Model
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
Energy level like rungs of the ladder
The electron cannot exist between energy
levels, just like you can’t stand between
rungs on a ladder
A quantum of energy is the amount of
energy required to move an electron from
one energy level to another
The Bohr Model
Energy level of an
electron analogous to
the rungs of a ladder
But, the rungs on this ladder
are not evenly spaced!
Quantum Mechanical Model
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Energy quantized; comes in chunks.
A quantum is the amount of energy
needed to move from one energy level to
another.
Since the energy of an atom is never “in
between” there must be a quantum leap
in energy.
1926 Erwin Schrodinger equation
described the energy and position of
electrons in an atom
Quantum Mechanical Model
•Things that are very small
behave differently from things
big enough to see.
•The quantum mechanical model
is a mathematical solution
•It is not like anything you can
see.
Quantum Mechanical Model
•Has energy levels for electrons.
•Orbits are not circular.
•It can only tell us the
probability of finding an
electron a certain distance
from the nucleus.
Atomic Orbitals
•Energy levels (n=1, n=2…)
•Energy sublevels = different
shapes
•The first energy level
has one sublevel:
1s orbital -spherical
Atomic Orbitals
•The second energy level has
two sublevels, 2s
and 2p
There are 3 p-orbitals
Atomic Orbitals
•The third energy level has three
sublevels, 3s
3p
And 5 3d orbitals
py
Atomic Orbitals
•The forth energy level has four
sublevels, 4s
4p
4d orbitals
And seven 4f orbitals
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T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
Atomic Orbitals
The principal quantum number
(energy level) equals the
number sublevels
5.2 Electron Arrangement in
Atoms
Electron Configuration
Electrons and nucleus interact
to produce most stable
arrangement=
Lowest energy configuration
3 rules:
Aufbau Principle Electrons fill
the lowest energy orbitals first
Hydrogen
has 1
electron
1
1s
3 rules:
Pauli Exclusion Principal- two
electrons per orbital (one spin
up, one spin down)
Boron has 5
electrons
2
2
1s 2s
1
2p
3 rules:
Hund’s rule- In orbitals with
equal energy levels, arrange
spin to maximize electrons with
22s22p3
1s
the same spin
Nitrogen has 7 electrons
Hund’s Rule: Separate the
three 2p elecrons into the
three available 2p orbitals
to maximize the electrons
with the same spin.
Conceptual Problem p135
Electron Configuration for Phosphorus (atomic # = 15)
1s2 2s2 2p6 3s2 3p3
Practice Problem 8a p135
Electron Configuration for Carbon (atomic number = 6)
1s2 2s2 2p2
Practice Problem 8b p135
Electron Configuration for Argon (atomic # = 18)
1s2 2s2 2p6 3s2 3p6
Practice Problem 8c p135
Electron Configuration for Nickel (atomic # = 28)
1s2 2s2 2p6 3s2 3p6 3d8 4s2
Practice Problem 9a p135
Electron Configuration for Boron (atomic # = 5)
1s2 2s2 2p1
How
many
unpair
ed
electro
ns?
1
Practice Problem 8c p135
Electron Configuration for Silicon (atomic # = 14)
1s2 2s2 2p6 3s2 3p2
How
many
unpair
ed
electro
ns?
2
Exceptions to the Aubau Rule
Copper atomic number=29
1s2 2s2 2p6 3s2 3p6 3d9 4s2
This is
the
expected
electron
configura
tion
Exceptions to the Aubau Rule
Copper atomic number=29
1s2 2s2 2p6 3s2 3p6 3d10 4s1
HalfThis is
filled
and
the
filled
actual
sublevels
electron
are
more
configura
stable,
tion.if it
even
means
stealing an
electron
from a
nearby
sublevel
Exceptions to the Aubau Rule
Chromium atomic number=24
1s2 2s2 2p6 3s2 3p6 3d4 4s2
This is
the
expected
electron
configura
tion
Exceptions to the Aubau Rule
Chromium atomic number=24
1s2 2s2 2p6 3s2 3p6 3d5 4s1
HalfThis is
filled
and
the
filled
actual
sublevels
electron
are
more
configura
stable,
tion.if it
even
means
stealing an
electron
from a
nearby
sublevel
5.3 Physics and the Quantum
Mechanical Model
Or, “How do they get all those colors of neon lights?”
QuickTime™
and
a a
QuickTime™
and
TIFFTIFF
(Uncompressed)
decompressor
(Uncompressed) decompressor
are are
needed
to see
thisthis
picture.
needed
to see
picture.
Goals
•Describe the relationship between wavelength
and frequency of light
•Identify the source of atomic emission
spectra
•Explain how frequency of emitted light are
related to changes in electron energies
•Distinguish between quantum mechanics and
classical mechanics
Quick review of wave terminology
Amplitude = height of wave
Wavelength = distance between crests
Frequency = number of crests to pass a point
per unit of time
Light waves
Amplitude = height of wave
Wavelength = distance between crests
Frequency = number of crests to pass a point
per unit of time
For light, the product of frequency and
wavelength = speed of light, c
Frequency • Wavelength = 3.00 x 108
So, as the frequency of light increases, the
wavelength decreases
Electromagnetic Spectrum
Visible light is only part of the
electromagnetic spectrum:
Wavelength of Light
p140
Sample Problem: What is
the wavelength of yellow
light from a sodium lamp if
the frequency is 5.10 x
1014 Hz (Hz = s-1)
Wavelength • frequency = 3.00x108m/s
Wavelength = 3.00x10-8 m/s / frequency
Wavelength = 3.00x108m/s / 5.10x1014 s-1
Wavelenght = 5.88 x 10-7 m
Wavelength of Light p140
#14:What is the wavelength of radiation
if the frequency is 1.50x1013 Hz (Hz = s-1)?
Is this longer or shorter than the wavelenght
of red light?
Wavelength • frequency = 3.00x108m/s
Wavelength = 3.00x108 m/s / frequency
Wavelength = 3.00x108m/s / 1.50x1013 s-1
Wavelength = 2.00 x 10-5 m
Longer than red lightwhich if between 10 and 10 m
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-7
Wavelength of Light p140
#15: What is the frequency of radiation
if the wavelength is 5.00x10-8 Hz (Hz = s-1)
In what range of the electromagnetic specrum is
this?
Wavelength • frequency = 3.00x108m/s
frequency = 3.00x108 m/s / wavelength
frequency = 3.00x108m/s / 5.00x10-8m
Frequency = 6.00 x 1015 s-1
ultraviolet
Atomic Spectra
When atoms absorb energy,
Electrons move to higher energy levels.
When electrons return to the lower energy
level, they emit light
Each energy level produces a certain frequency
of light resulting in an emission spectrum
Atomic Spectra
Emission spectra are like a fingerprint of the
element
We know what stars are made of by comparing
their emission spectra to that of elements we
find on earth
Explanation of Atomic Spectra
Emission spectra like a fingerprint of the
element
We know what stars are made of by comparing
their emission spectra to that of elements we
find on earth