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CHAPTER 5
ELECTRON CONFIGURATION
ANALOGY OF THE ATOM
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UNITED STATES
NEW JERSEY
MIDDLESEX
COUNTY
EDISON
Township
YOUR HOUSE
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ATOM
ENERGY LEVEL
SUBLEVEL
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ORBITAL
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LOCATION OF
ELECTRON
1.Principle Energy Levels: (n = 1,2,3….7) a.k.a
shells
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Different values of n = different energy levels
& different electron energies
Maximum number of e- each level holds is
found by:
2n2
EX: 1st energy level (n=1)
2n2 = 2(1)2 = 2 electrons in 1st energy level
Increasing energy level
n=
1
2
Max #
2
8
of e-s
Increasing distance from nucleus
3
4
18
32
2.Sublevels:
s (spherical), p (dumbbell), d, f
 Cloud shapes
 The # of energy sublevels is the same as the
energy level #
Energy Level (n)
# of Sublevels
Type of Sublevel
n=1
1
1s
n=2
2
2s2p
n=3
3
3s3p3d
n=4
4
4s4p4d4f
3.Orbitals:
 Each sublevel has a different # of orbitals which
means a different # of electrons
 The # of orbitals in an energy level is found by:
n2
EX: 3rd energy level (n=3)
32 = 9 orbitals
This makes sense because:
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3rd energy level would have 3 sublevels;
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s sublevel with 1 orbital,
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p sublevel with 3 orbitals, and
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d sublevel with 5 orbitals.
 SO……1 + 3 + 5 = 9, so the formula n2 works!
Sublevel(s)
# of orbitals
n2
s
1
Maximum # of
e-s
2n2
2
s,p
4
8
s,p,d
9
18
s,p,d,f
16
32
PRACTICE
Principle Energy Level
5
2p
Number of
Electrons in
Sublevel
Type of Electron Sublevel
Orbitals and Electron Capacity of the First Four Principle
Energy Levels
# of
Maximum
Principle
# of
Type of
orbitals
# of
energy
orbitals
sublevel
per level
electrons
level (n)
per type
(n2)
(2n2)
1
s
1
1
2
s
1
2
4
8
p
3
s
1
3
p
3
9
18
d
5
s
1
p
3
4
16
32
d
5
f
7
HOW TO DETERMINE ELECTRON
CONFIGURATIONS
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How electrons are arranged around the
nuclei of atoms
3 RULES:
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Aufbau
Pauli Exclusion Principle
Hund’s Rule
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Aufbau Principle:
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Electrons enter orbitals of lowest energy level 1st
Start at the beginning of each arrow, and then
follow it all of the way to the end.
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
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2. Pauli Exclusion Principle:
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Orbitals can hold only 2 electrons
Each electron in the orbital has an opposite spin
1s2
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3. Hund’s Rule:
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One electron enters each orbital until all orbitals
contain one electron with parallel spins.
1s2
1s2
2s2
2s2
2p3
2p4
Bohr ModelLine Spectra Explained
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Electrons can occupy specific energy levels
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Excited atoms can emit light
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Each orbital they are in has specific energy.
Atomic Emission Spectrum
Spectrometer: Breaks up what we see as
continuous light into individual bands of light.
The individual bands of light represent the
exact frequency of light be given off.
This corresponds to the quantum of energy that
is released when an electron goes from an
excited state to the ground state.
Electrons move from ground state to an excited
state and back again.
The bands of light are called:
ATOMIC EMISSION SPECTRUM
This spectrum is unique to every element.
Atomic Emission Spectrum
Add
energy
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Different elements are used to give fireworks
their color!
To learn more about the science of fireworks
see:
http://www.pbs.org/wgbh/nova/kaboom/
Electromagnetic Spectrum
How Does the Atomic Emission
Spectrum Correspond to Electron
Configuration?
1. Electrons get excited when we introduce
ENERGY (fire, electricity, light)
2. Electrons jump from ground state to an
excited state
3. The amount of energy needed to do this
is a QUANTUM of energy
QUANTUM: is the amount of energy needed to
move an electron from one energy level to the
next.
4. Electrons go back to the ground state and
give off this energy in the form of light
(PHOTONS)
PHOTON: a quantum of light; a discrete
amount of energy that behaves as a particle.
E= h c / l
E= Energy
h= Planck’s constant
c= speed of light
l=wavelength