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Electron Electron ConfigurationConfiguration
UNIT 4 – QUANTUM MODEL:
Warm UpWarm Up•Where are the s, p, d, f orbitals located on the periodic table?
AgendaAgenda•Quiz•Grade Homework•Unit 4: Electron Configuration•Homework
- Catch up on work even if it’s LATE!
© 1998 by Harcourt Brace & Company
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Electron Electron Configuration:Configuration:
•The arrangement of electrons in an atom
•Quantum model states that electrons are found in Orbitals: •a 3-D space around the nucleus (“electron cloud”)
•Electron Orbitals:
Electron Configuration:Electron Configuration:
s p d f
•Orbitals correspond to sublevels on the periodic table1
2
3
4 5
6
7
Electron Electron Configuration:Configuration:
sd p
fPeriod
(Energy
level )
1. Aufbau Principle
Electrons occupy the lowest energy orbitals first - “Lazy Tenant Rule”
s p d f
Electron Configuration Electron Configuration Rules:Rules:
Orbitals are in
order of increasing
energy
Electron Configuration Electron Configuration Rules:Rules:
2.Pauli Exclusion Principle: Each orbital can hold
TWO electrons with opposite spins.
(Orbital diagram
notation)
RIGHTWRONG
Electron Configuration Electron Configuration Rules:Rules:
3.Hund’s Rule Within a sublevel, place one
e- per orbital before pairing them.
“Empty Bus Seat Rule”
Electron ConfigurationElectron Configuration
Energy sublevel
Energy Level (Period #)
1s1# of e- in sub level
•What element? ____________ Hydrogen
1s
Electron ConfigurationElectron Configuration
1s2
•What element? ____________ Helium 1s
Electron ConfigurationElectron Configuration
•What element? ____________ Lithium
1s2 2s1
1s 2s
Electron ConfigurationElectron Configuration
•What element? ____________ BERYLLIUM
1s2 2s2
1s 2s
1s2
Electron ConfigurationElectron Configuration
Phophorus
2s2 2p6 3s2 3p3
O
8e-
•Orbital Diagram
•Electron Configuration
1s2 2s2 2p4
Electron ConfigurationElectron Configuration
1s 2s 2p
O 8e-
© 1998 by Harcourt Brace & Company
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Core vs. Valence Core vs. Valence ElectronsElectrons
Core electrons:
electrons found on the inner energy levels
Valence Electrons:
electrons found on the outer-most energy level
1s2 2s2 2p6 3s2 3p3
S 16e-
Valence Electrons
Core Electrons
Mg 12e-
1s2 2s2 2p6 3s2 3p4
Core vs. Valence Core vs. Valence ElectronsElectrons
1s2 2s2 2p63s2
Label the Label the following in following in your P. your P. table:table:
Noble Gases
Noble Gas NotationNoble Gas Notation• Noble Gas Notation
1. Write the noble gas of previous row in brackets (Core e-)
2. Fill in the rest of the configuration (Valence e-).
Ex: Ca 20 e- Cl 17 e-
[Ar]4s2 [Ne]3s23p5
•Noble Gas Notation
(shorthand)
S 16e-
Valence Electrons
Core Electrons
S 16e- [Ne]
1s2 2s2 2p6 3s2 3p4
Noble Gas NotationNoble Gas Notation•Regular Notation (longhand)
3s2 3p4
Why do the elements in Why do the elements in the f-block sit below the the f-block sit below the
rest of the Periodic table?rest of the Periodic table?
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© 1998 by Harcourt Brace & Company
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