Download Notes: Electron Configurations

Electron
Configurations
Electron Configurations
The quantum mechanical model of the atom
predicts energy levels for electrons; it is
concerned with probability, or likelihood, of
finding electrons in a certain position.
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“Any one who is not shocked
by Quantum theory does
not understand it.”
Niels Bohr
Electron Configurations
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Electron Configurations
Regions where electrons are likely to be
found are called orbitals. EACH ORBITAL
CAN HOLD UP TO 2 ELECTRONS!
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Electron Configurations
In quantum theory, each electron is assigned
a set of quantum numbers
z analogy: like the mailing address of an
electron
Electron Configurations
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Electron Configurations
Playing Chopin with Boxing Gloves
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“Trying to capture the physicists’ precise
mathematical description of the quantum
world with our crude words and mental
images is like playing Chopin with a
boxing glove on one hand and a catcher’s
mitt on the other.”
(1996). Johnson, George. On skinning Schrodinger’s Cat.
New York Times.
Principal Quantum Number (n)
Erwin Schrödinger
I don’t like it, and
I’m sorry I ever had
anything to do with
it.
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Describes the energy level that the electron
occupies
n=1
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n=1, 2, 3, 4
n=2
n=3
n=4
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The larger the value of n, the farther away
from the nucleus and the higher the energy of
the electron.
Sublevels (l)
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The number of sublevels in each energy level
is equal to the quantum number, n, for that
energy level.
Sublevels are labeled with a number that is
the principal quantum #, and a letter: s, p, d, f
(ex: 2 p is the p sublevel in the 2nd energy level)
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Sublevels (l)
Sublevels (l)
Principal Energy Level
Sublevels
Orbitals
n=1
1s
one (1s)
n=2
2s
2p
one (2s)
three (2p)
n=3
3s
3p
3d
one (3s)
three (3p)
five (3d)
4s
4p
4d
4f
one (4s)
three (4p)
five (4d)
seven (4f)
n=4
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Labels the orientation of the electron
Electrons in an orbital spin in opposite
directions; these directions are
designated as +1/2 and -1/2
Orbitals of equal energy are each occupied
by one electron before any pairing occurs.
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z
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Max # of electrons
s
1
2
p
3
6
d
5
10
f
7
14
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States that no 2 electrons have an
identical set of four quantum #’s to
ensure that no more than 2 electrons can
be found within a particular orbital.
Orbital Diagrams
Hund’s Rule
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# of orbitals
Pauli Exclusion Principle
Spin quantum number (ms)
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Sublevel
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Each orbital is represented by a box.
Each electron is represented by an arrow.
Repulsion between electrons in a single orbital is
minimized
All electrons in singly occupied orbital must
have the same spin.
When 2 electrons occupy an orbital they have
opposite spins.
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Complete electron configurations
Orbital Diagrams
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1s
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helium
1s2
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boron
1s22s22p1
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neon
1s22s22p6
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aluminum 1s22s22p63s23p1
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uranium
hydrogen
helium
1s
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carbon
1s
2s
2p
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f4
Abbreviated electron diagrams
1s2
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helium
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boron
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aluminum [Ne]3s23p1
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cobalt
[He]2s22p1
[Ar]4s23d7
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N3-
[He]2s22p6
= [Ne]
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Se2-
[Kr]
z Mg2+
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uranium
[Rn]7s25f4
[Ne]
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