electrons in atoms: electron configuration
TRANSCRIPT
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Electron
Configuration
Electrons in Atoms
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A. General Rules
Pauli Exclusion Principle
Each orbital can hold TWO electronswith opposite spins.
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A. General Rules
Aufbau Principle
Electrons fill the
lowest energy
orbitals first.
Building Up
Principle
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s px py pz
dxy dxz dyz dz2 dx
2-y
2
f xz2 f yz2 f xyz f z(x2-y2) f x(x2-3y2) f y(3y2-x2) f z3
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0 -1 0 +1
-2 -1 0 +1 +2
-3 -2 -1 0 +1 +2 +3
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RIGHTWRONG
A. General Rules
Hund’s Rule
Within a sublevel, place one
electron per orbital before
pairing them.
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O8e-
Orbital Diagram/Box (Electronic Structure)
Electron Configuration
1s2 2s2 2p4
B. Notation
1s 2s 2p
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Abbreviated/Shorthand/Noble Gas
Configuration
S 16e-
Valence Electrons(Valence Shell)
Core/Kernel Electrons(Kernel Shell)
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
B. Notation
Longhand Configuration
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Ne
1s2 2s2 2p6
3s2
3p4
Ne 10e-
S 16e- 1s2
2s2
2p6
S 16e- [Ne] 3s2 3p4
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Electron Configuration and
Quantum Numbers
1s2 2s2 2p4O 8e-
Identify the four quantum numbers of the
third electron.
2s2
2 0 0 +½
0
El t i ti d
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Electron on iguration andQuantum Numbers
Identify the electron configuration of theatom if its last electron in the valence shellhas the following set of quantum numbers.
2 1 -1 +½
2p11s2 2s2
-1 0 +1
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© 1998 by Harcourt Brace & Company
s p
d (n-1)
f (n-2)
1
2
3
4
5
6
7
6
7
C. Periodic Patterns
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C. Periodic Patterns
Period/Series number
energy level (subtract for d & f)
Group number (A/B Family)
total number of valence electrons
Column within sublevel block
number of electrons in sublevel
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s-blockPeriod 1
1s1Group 1
C. Periodic Patterns
Example - Hydrogen
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1
2
3
4
5
6
7
C. Periodic Patterns
Shorthand Configuration Core electrons: Go up one row and
over to the Noble Gas.
Valence electrons: On the next row, fillin the number of electrons in eachsublevel.
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[Ar] 4s2 3d10 4p2
C. Periodic Patterns
Example - Germanium
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Fully filled energy level
1
2
3
4
5
6
7
Fully filled sublevel (s, p, d, f)
Half-filled sublevel
D. Stability
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Electron Configuration Exceptions
Copper
EXPECTED: [Ar] 4s2 3d9
ACTUAL: [Ar] 4s1 3d10
Copper gains stability with a fully filled
d-sublevel.
D. Stability
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Electron Configuration Exceptions
Chromium
EXPECTED: [Ar] 4s2 3d4
ACTUAL: [Ar] 4s1 3d5
Chromium gains stability with a half-filled
d-sublevel.
D. Stability
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D. Stability
Ion Formation
Atoms gain or lose electrons to become
more stable.
Isoelectronic with the Noble Gases.
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O2- 10e- [He] 2s2 2p6
D. Stability
Ion Electron Configuration
Write the electron configuration for the
closest Noble Gas
Ex: Oxygen ion → O2- ≡ Ne
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Li+ 2e- 1s2
D. Stability
Ex: Lithium ion → Li+ ≡ He