Transcript Chpt8elecConfig - Mr-Watson-General-Chemistry-A

Chapter 8
Electron Configuration and Periodicity
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Orbitals

region of probability of finding an electron
around the nucleus
 4 types => s p d f
 maximum of 2 electrons per orbital
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Pure Atomic Orbitals
s
p
d
f
shape
# of orbitals / energy level
spherical
1
dumbbell
3
complex
5
very complex
7
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Pauli Exclusion Principle
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Electronic Configurations

The shorthand representation of the
occupancy of the energy levels (shells and
subshells) of an atom by electrons.
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Electronic Configuration
shells
subshells
=>
=>
energy levels
orbitals
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Regions by Electron Type
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Electron Filling Order
Diagram
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
3d
4d 4f
5d 5f
6d
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Electronic Configuration
H atom
1 electron
1s1
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Electronic Configuration
He atom
2 electrons
1s2
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Electronic Configuration
Li atom
3 electrons
1s2, 2s1
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Electronic Configuration
Cl atom
17 electrons
1s2, 2s2, 2p6, 3s2, 3p5
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Electronic Configuration
As atom
33 electons
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p3
or
[Ar] 4s2, 3d10, 4p3
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Mn: [Ar]4s2 3d?
How many d electrons does Mn have?
4, 5, 6
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Electronic Configuration
negative ions
add electron(s), 1 electron for each negative
charge
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Electronic Configuration
S-2 ion
(16 + 2)electrons
1s2, 2s2, 2p6, 3s2, 3p6
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Electronic Configuration
positive ions
remove electron(s), 1 electron for each
positive charge
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Electronic Configuration
Mg+2 ion
(12-2)electrons
1s2, 2s2, 2p6
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How many valence electrons are in Cl,
[Ne]3s2 3p5?
2, 5, 7
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For Cl to achieve a noble gas configuration,
it is more likely that
electrons would be added
electrons would be removed
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Trends in the
Periodic Table

atomic radius
 ionic radius
 ionization energy
 electron affinity
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Atomic Radius

decrease left to right across a period
– as nuclear charge increases, number of
electrons increase; however, the nucleus acts as
a unit charge while the electrons act
independently, pulling electrons towards the
nucleus, decreasing size
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Atomic Radius

increase top to bottom down a group
– each additional electron “shell” shields the
outer electrons from the nuclear charge
Zeff = Z - S
where Zeff => effective nuclear charge
Z => nuclear charge, atomic number
S => shielding constant
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Atomic Radius

increases from upper right corner to the
lower left corner
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Atomic Radius vs. Atomic Number
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Atomic Radius
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Ionic Radius

same trends as for atomic radius
 positive ions smaller than atom
 negative ions larger than atom
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Ionic Radius
Isoelectronic Series
 series of negative ions, noble gas atom, and
positive ions with the same electronic
confiuration
 size decreases as “positive charge” of the
nucleus increases
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Ge is a semiconductor. If half of the Ge
atoms of a sample of Ge are replaced with
Ga atoms, with what element should the
other half of the Ga atoms be replaced in
order for this new compound to be
isoelectronic with Ge?
Sn, As, Se
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Ionization Energy

energy necessary to remove an electron to
form a positive ion
 low value for metals, electrons easily
removed
 high value for non-metals, electrons
difficult to remove
 increases from lower left corner of periodic
table to the upper right corner
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Ionization Energies
first ionization energy
 energy to remove first electron from an
atom
second ionization energy
 energy to remove second electron from a +1
ion
etc.
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Ionization Energy vs. Atomic Number
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Electron Affinity

energy released when an electron is added
to an atom
 same trends as ionization energy, increases
from lower left corner to the upper right
corner
 metals have low “EA”
 nonmetals have high “EA”
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Magnetism

Result of the spin of electrons
 diamagnetism - no unpaired electrons
 paramagnetism - one or more unpaired
electrons
 ferromagentism - case of paramagnetism
where the substance retains its magnetism
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Magnetism
Without applied field
Without applied field
With applied field
With applied field
Paramagnetism
Ferromagnetism
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