Subshells and Orbitals
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Transcript of Subshells and Orbitals
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Timberlake LecturePLUS 2000
Subshells and Orbitals
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Timberlake LecturePLUS 2000
Quantum Mechanics
Describes the arrangement of electrons
in atoms in terms of:
Main or principal energy levels (n)
Energy subshells
Orbitals (space occupied within the
atom)
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Principal Energy Levels (n)
Contain electrons that are
Close in energy
Similar distance from nucleusHave values of n = 1, 2, 3, 4, 5, 6..
Maximum number of electrons = 2n2
n =1 2(1)2 = 2
n =2 2(2)2 =8
n=3
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Timberlake LecturePLUS 2000
Energy Levels (Shells)
A group of electrons in an atom all having the
same principal quantum number (n)
n = 1, 2, 3,
The first shell (n = 1) is lowest in energy,
2ndlevel next and so on 1
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Energy Levels for Electrons
Some possible electron transitions for the first
three energy levels are shown below. The
negative value means that the electron in the
atom has a lower energy than a free electronEnergy Level Energy, E
n=3 ___________________ (-) 2.420 x 1019J
n=2 __________________ (-) 5.445 x 1019J
n=1 __________________ (-) 2.178 x 1018
J
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Timberlake LecturePLUS 2000
Learning Check S1
A. What energy change (J) takes place when an
electron in a hydrogen atom moves from the
first (n=1) to the second shell (n=2)?
B. What energy change (J) takes place when
the electron moves from the third shell to thesecond shell?
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Timberlake LecturePLUS 2000
Solution S1
A. What energy change takes place when an
electron in a hydrogen atom moves from the
first (n=1) to the second shell (n=2)?
1.634 x 10-18J of energy must be absorbed.
B. What energy change takes place when the
electron moves from the third shell to the
second shell?(-5.445 x 10-19J)-(2.2420 x 10-19J)= -3.025 x
1019J will be em it ted as electro n fal ls from a
higher to a lower energy state
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Timberlake LecturePLUS 2000
Subshells
Energy sublevels within energy level
All electrons in a subshell have the
same energy
Designated s , p , d , f ..Sublevel energy: s
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Timberlake LecturePLUS 2000
Electron Locations
Main
Energy
Levels Sublevels
n=4 4s, 4p, 4d, 4f
n=3 3s, 3p, 3d
n=2 2s, 2p
n=1 1s
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Timberlake LecturePLUS 2000
Sublevels in n = 1,2, 3
3d
n = 3 3p
3s
2p
n = 2 2s
n = 1 1s
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Timberlake LecturePLUS 2000
Electrons Allowed
All electrons in the same sublevel have the sameenergy.
All 2s electrons have the same energy. All 2p
electrons have the same energy which is slightlyhigher than the energy of the 2s electrons
s sublevel 2electrons
p sublevel 6electronsd sublevel 10electrons
f sublevel 14electrons
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Timberlake LecturePLUS 2000
Electron Configuration
List of subshells containing electrons
Written in order of increasing energy
Superscripts give the number of electrons
Example: Electron configuration of neon
number of electrons
1s2 2s2 2p6
main shell subshell
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Order of Filling
Total energy of a subshell =energy of the main shell + the subshell
The 4s energy < 3d energy
4p ___
3d ___ (finishes the n=3 shell)
4s ___ (starts the n=4 shell)
3p ___
3s ___
2p ___
2s ___
1s ___
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Timberlake LecturePLUS 2000
Writing Electron Configurations
H 1s1
He 1s2
Li 1s2 2s1
C 1s2
2s2
2p2
S 1s2 2s2 2p6 3s2 3p4
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Sublevel Blocks
s1 s2 p1p2 p3 p4p5p6
1
2
3 d1- d10
4
56
f1- f14
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Find the element on the periodic
table
Use the order of filling indicatedacross each period
Groups 1-2 = s level
Groups 3-8 = p levelTransition = d level
Lantanides = f level
Periodic Table and Electron
Configuration
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Learning Check S2
Indicate if each configuration is (1) correct or
(2) incorrect for potassium. Give an
explanation for selection of 1 or 2. Explain
why or why not?
A. 1s22s22p63s1 1 or 2
B. 1s22s22p63s23p6 1 or 2
C. 1s22s22p63s23p64s1 1 or 2
D. 1s22p83s1 1 or 2
E. 1s2
2s2
2p6
3s2
3p7
1 or 2
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Solution E2
For phosphorus,indicate if each
configuration is (1) correct or (2) incorrect.
Explain why or why not.
A. 2, 2, 8, 5 2
B. 2, 8, 3 2
C. 2, 8, 5 1
D. 2, 6, 7 2
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Timberlake LecturePLUS 2000
Learning Check S3
Using the periodic table, write the complete
electronic configuration for each:
A. Cl
B. Sr
C. I
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Solution S3
Using the periodic table, write the complete
electronic configuration for each:
A. Cl1s22s2 2p63s23p5
B. Sr
1s22s2 2p63s23p64s23d10 4p65s2
C. I
1s22s2 2p63s23p64s23d10 4p65s2 4d105p5
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Timberlake LecturePLUS 2000
Learning Check S4
A. The final two notations for Co are
1) 3p64s2
2) 4s2
4d7
3) 4s23d7
B. The final three notations for Sn are
1) 5s25p24d10
2) 5s24d105p2
3) 5s25d105p2
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Solution S4
A. The final two notations for Co are
3) 4s2 3d7
B. The final three notations for Sn are
2) 5s2 4d10 5p2
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Orbital
A 3 dimensional space around a nucleus in
which electrons are most likely to be found
Shape represents electron density (no t a
path the electron fol low s)
Each orbital can hold up to 2 electrons.
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s orbitals
1s 2s 3s
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Three p Orbitals
px pz py
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p subshell contains p orbitals
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d orbitals
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Learning Check S5
A. Number of electrons in a p orbital
1) 1e 2) 1e or 2e 3) 3e
B. Number of orbitals in a p subshell1) 1 2) 2 3) 3
C. Number of orbitals in 4d subshell
1) 1 2) 3 3) 5
D. Number of electrons (maximum) in a 3dsubshell
1) 2e 2) 5e 3) 10e
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Timberlake LecturePLUS 2000
Solution S5
A. Number of electrons in a p orbital
2) 1e or 2e
B. Number of orbitals in a p subshell
3) 3
C. Number of orbitals in 4d subshell3) 5
D. Number of electrons in a 3d subshell
3) 10e