Transcript Energy Levels

Agenda – October 6-7, 2010
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Review Homework
Problem-Solving Strategies
 GUESS
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Flame Test
 Introduction to Orbitals and Electron
Configuration
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Assignment
• Study!!
• Quiz next class!!
Review EM Spectrum:
• Which has a LONGER wavelength: red or
blue light?
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If gamma rays have a very high frequency,
what can be said of its wavelength and
energy?
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If gamma rays have a very high frequency,
what can be said of its wavelength and
energy?
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How are wavelength and frequency
related?
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Wavelength & frequency are INVERSELY
related.
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If one goes UP, the other goes DOWN
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How are energy and frequency related?
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Energy and frequency are DIRECTLY
proportional
Electromagnetic Radiation
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Better known as light.
Small wavelengths mean high energy.
We see light that has wavelengths from 400 –
700 nanometers (1 billionth of a meter).
Light that is lower in energy than visible light is
Infrared, Microwaves, and Radio waves.
Light that is higher in energy is ultraviolet, Xrays, and Gamma rays
We see light because it is reflected in our eyes.
We see color because some light is absorbed
while other light is reflected.
Gas Discharge Tubes
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Atoms absorb and release energy from the
electricity sent through the tubes.
Since electrons are on the outside of the atom,
they must be absorbing and releasing the
energy.
If you use a prism, you can refract the light that
comes from each tube.
When you examine the light emission from
elements, each has its own characteristic set of
lines.
Gases in Discharge Tubes
Warm-up 10/7
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Calculate the frequency of a photon whose
wavelength is 3.25X10^-5m.
Line-Emission Spectrum
excited state
ENERGY IN
PHOTON OUT
ground state
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Ground state of an electron, the energy
level it normally occupies, is the state of
lowest energy for that electron.
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Excited state-When an electron
temporarily occupies an energy state
greater than its ground state
Emission Spectrum
The Hydrogen Emission Spectrum
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Niels Bohr examined the hydrogen emission spectrum
and thought that since the lines were producing specific
energies, electrons must have specific energies around
the atom.
He called these energy levels quanta. (Quantum is the
singular form of the word.)
Bohr’s Model of the Atom
Bohr’s Model of the Atom
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Electrons exist only in orbits with specific
energy called energy levels (the rings)
e- CANT exist
between energy
levels
4
3
2
1
Therefore…
e- can only
gain or lose
certain
amounts of
energy
only certain
photons are
produced
Bohr Model
65
4
Energy
3
2
1
of photon
depends on the
difference in energy
levels
Electrons in Bohr Model
Depending
on amount
of energy
released,
you’ll see a
certain
color
Quantum Theory of the Atom
(where are electrons located?)
Exactly Where are Electrons
Located?
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It is impossible to determine the exact
momentum and position of e-
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There are FOUR “quantum numbers” that can
determine the PROBABILITY where the
electrons are
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Think about electrons staying in “hotel atom”
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They can be in different hotel floors, rooms, and
in different sizes of beds.
Energy Levels
Energy levels corresponds to energy of
electron. (Each has its own numerical
value)
 2n² tells you how many e- in each level
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1st energy level (n=1)
2nd energy level (n=2)
Maximum amount eEnergy Level
# electrons
(2n²)
1
2
2
8
3
18
4
32
The FOUR Principal Quantum
Numbers
#1 Principal Quantum number (n)
Energy level (1, 2, 3, 4)
 More energy as level
increases
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“Hotel floor”
#2 Sublevels
“Azimuthal Quantum Number”
The space where you’ll PROBABLY find
an e 4 types: s, p, d, f
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“hotel room shape”
s
p
d
f
#3 ORBITALS
“Magnetic Quantum Number”
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Energy shift- Orientation of orbital
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Number of “beds” vary for each room
shape
s = 1 “bed”
 p = 3 “beds”
 d = 5 “beds”
 f = 7 “beds”
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#4 Spin Projection Quantum
Number
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Tells you the direction e- spins
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Each orbital (bed) can hold two e- with
opposite spins
Review “Electron Cloud Hotel”
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Energy levels = “floors”
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Sublevels = “room shape”
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s, p, d, f
Orbitals = “# of beds”
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1-8
s= 1, p = 3, d= 5, f = 7
Only 2 electrons in each orbital/bed spinning in
opposite direction
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s= 2 e-, p = 6 e-, d = 10 e-, f = 14 e-
How to fill e- in their energy levels:
Electrons are lazy, so they fill lowest energy
level first
Periodic Patterns!
Patterns in the periodic table 