e_congif

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Rules of Electron Etiquette
Aufbau Principle Electrons always seek the
lowest energy level
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Rules of Electron Etiquette
Pauli Exclusion Principle Since electrons
possess spin, (ms 1/2, -1/2),
an orbital may hold at most two electrons of
opposite spin
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Rules of Electron Etiquette
Hunds Rule electrons occupy degenerate
orbitals to the greatest extent possible and
with their spins parallel
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As the quantum energy levels increase...
...they tend to compress upon one another
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So if we consider the element calcium, here is
what happens
2p6
2s2
3s2
Ca1s2
3p6
4s2
We may then abbreviate the e-config as
CaAr4s2
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Historical Development of the Periodic Table
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Periodic Trends in the Elements
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Understanding Effective Nuclear Charge
Na1s22s22p63s1
Na has 11 protons (Z 11)
Na has 10 core electrons (S 10 e-)
Zeff Z - S 11 - 10 1
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Understanding Effective Nuclear Charge
Mg1s22s22p63s2
Mg has 12 protons (Z 12)
Mg has 10 core electrons (S 10 e-)
Zeff Z - S 12 - 10 2
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Periodic Trends in the Elements
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Periodic Trends in the Elements
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Periodic Trends in the Elements
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Periodic Trends in the Elements
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Periodic Trends in the Elements
Electronegativity
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The Key to Why Reactions Occur is the 8A group
The Noble Gases
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Why do Reactions Occur?
1s2
1s22s22p6
1s22s22p63s23p6
1s22s22p63s23p64s23d104p6
1s22s22p63s23p64s23d104p65s24d105p6
Xe6s24f145d106p6
Outer valence shell is complete
Outer valence shell possesses 8 valence electrons
The Nobel gases have completed octets
Noble gases are stable elements
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Why do Reactions Occur?
Does not have a completed octet
Sodium would be more stable...
if it had a completed octet.
Soif sodium lost a valence electron...
Na1s22s22p63s1
it would have a completed octet
Na1s22s22p6
The sodium ion is now isoelectric to neon
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Why do Reactions Occur?
Does not have a completed octet
Chlorine would be more stable...
if it had a completed octet.
Soif chlorine gained a valence electron...
Cl 1s22s22p63s23p5
it would have a completed octet
Cl- 1s22s22p63s23p6
The Chloride ion is now isoelectric to neon
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