AP Chemistry
Unit 3 - Elements
Lesson 11 – Orbital
Representations
Book Section: 6.4-6.9
Orbital Diagrams
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Each box in the
diagram represents
one orbital.
Half-arrows represent
the electrons.
The direction of the
arrow represents the
relative spin of the
electron.
Hund’s Rule
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For degenerate orbitals,
the lowest energy is
attained when the number
of electrons with the same
spin is maximized.
Make all degenerate
orbitals half-filled before
adding the opposite spin
electrons.
Half-filled subshells (p3,
d5), are especially stable.
Magnetism
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Magnetism results from unpaired electrons in the
ground state.
When there are multiple unpaired electrons (like
in iron), this results in a ferromagnet, or
permanent magnet, or a paramagnet, or
temporary magnet.
1984 MC #66
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A)
B)
C)
D)
E)
Ca, V, Co, Zn, As
Gaseous atoms of which of the following
elements above are paramagnetic?
Ca and As
Zn and As
Ca, V, and Co
V, Co, and As
V, Co, and Zn
1984 MC #66


A)
B)
C)
D)
E)
Ca, V, Co, Zn, As
Gaseous atoms of which of the following
elements above are paramagnetic?
Ca and As
Zn and As
Ca, V, and Co
V, Co, and As – 42% correct, medium
V, Co, and Zn
1994 MC #1-4
Heisenberg uncertainty principle
B)
Pauli exclusion principle
C) Hund’s rule (principle of maximum multiplicity)
D) Shielding effect
E)
Wave nature of matter
1) Can be used to predict that a gaseous carbon atom in its
ground state is paramagnetic.
2) Explains the experimental phenomenon of electron
diffraction
3) Indicates that an atomic orbital can hold no more than two
electrons
4) Predicts that it is impossible to determine simultaneously
the exact position and exact velocity of an electron.
A)
1994 MC #1-4
Heisenberg uncertainty principle
B)
Pauli exclusion principle
C) Hund’s rule (principle of maximum multiplicity)
D) Shielding effect
E)
Wave nature of matter
1) Can be used to predict that a gaseous carbon atom in its
ground state is paramagnetic. C – 32% correct, hard
2) Explains the experimental phenomenon of electron
diffraction E – 38% correct, hard
3) Indicates that an atomic orbital can hold no more than two
electrons B - 44% correct, medium
4) Predicts that it is impossible to determine simultaneously
the exact position and exact velocity of an electron., A –
82% correct, very easy
A)
1999 MC #5-8
1s ___ 2s ___
B)
1s ___ 2s ___
C) 1s ___ 2s ___ 2p ___ ___ ___
D) 1s ___ 2s ___ 2p ___ ___ ___
E)
[Ar] 4s ___ 3d ___ ___ ___ ___ ___
5) Represents an atom that is chemically unreactive
6) Represents an atom in an excited state
7) Represents an atom that has four valence electrons
8) Represents an atom of a transition metal
A)
HW: 6.60, 62, 63, 64, 66
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Next Week:
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Thursday– Periodic Trends
Friday – Radioactive Decay & Nuclear Equations
10/18 – Gravimetric Analysis of a Chloride
Salt Due
10/20 – Elements Exam
10/21 – Problem Set 2 Due