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Chemistry Notes. Electron Configurations. Electron Configurations. Studying the arrangement of electrons in atoms helps one understand chemical activity. From an electron configuration you can determine: Most stable electron arrangement Charge Bonding patterns Etc. - PowerPoint PPT PresentationTRANSCRIPT
Chemistry NotesChemistry Notes
Electron ConfigurationsElectron Configurations
Electron Configurations Electron Configurations
Studying the arrangement of electrons Studying the arrangement of electrons in atoms helps one understand in atoms helps one understand chemical activity.chemical activity.
From an electron configuration you can From an electron configuration you can determine:determine: Most stable electron arrangement Most stable electron arrangement ChargeCharge Bonding patternsBonding patterns Etc.Etc.
Electron ConfigurationsElectron Configurations
Electron Configurations:Electron Configurations: Shows the Shows the Principle Energy Levels, the sublevels and Principle Energy Levels, the sublevels and the number of electrons in those the number of electrons in those sublevels.sublevels.
Examples of electron configurations:Examples of electron configurations:H H 1s 1s11
He He 1s 1s22
Li Li 1s 1s222s2s11
O O 1s 1s222s2s222p2p44
Electron ConfigurationsElectron Configurations
Electron ConfigurationsElectron Configurations
Rule to remember when writing an Rule to remember when writing an electron configuration for a certain atom:electron configuration for a certain atom:
Auf Bau PrincipleAuf Bau Principle – – The lowest energy The lowest energy levels fill first in atomslevels fill first in atoms Some Energy Levels do overlapSome Energy Levels do overlap
In atoms a In atoms a 4s 4s level will fill before a level will fill before a 3d3d level level because the because the 4s4s sublevel has a sublevel has a lower energylower energy than the than the 3d3d..
Electron ConfigurationsElectron Configurations
Notice: the 4s is lower in energy than the Notice: the 4s is lower in energy than the 3d sublevel, therefore, it fills first.3d sublevel, therefore, it fills first.
Electron ConfigurationsElectron ConfigurationsStart at the top of the arrow, go down. Once you are at the head of the arrow go to the top of the next. Repeat until you have reached the desired number of electrons.
Using this diagram can help you understand how to write the correct electron configuration for each atom.
Electron ConfigurationsElectron ConfigurationsEX: Ag has 47 electronsEX: Ag has 47 electrons
Fill sublevels unit they add up to 47.Remember how many electrons can go in each sublevel.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d9
s = 2
p = 6
d = 10
f = 14
Notice: the last sublevel only contains 9 (not 10) electrons
Electron ConfigurationsElectron Configurations
Another Ex: Another Ex: Titanium has 22 electrons
Ti: 1s2 2s2 2p6 3s2 3p6 4s2 3d2
2 6 10 14
Electron ConfigurationsElectron Configurations
Here is a similar diagram for ECHere is a similar diagram for EC
Electron ConfigurationsElectron Configurations
EC can be abbreviated EC can be abbreviated a noble a noble gas configuration (seen below).gas configuration (seen below).
Element ZElectron
Configuration
Noble Gas Configuration
Scandium 211s2 2s2 2p6 3s2 3p6 4s2
3d1
[Ar] 4s2 3d1
Titanium 221s2 2s2 2p6 3s2 3p6 4s2
3d2
[Ar] 4s2 3d2
Vanadium 231s2 2s2 2p6 3s2 3p6 4s2
3d3
[Ar] 4s2 3d3Notice: [Ar] represents the EC of Argon
Orbital Filling DiagramsOrbital Filling DiagramsAn orbital diagram give more detailed An orbital diagram give more detailed information than an electron configuration.information than an electron configuration.
Boxes or blanks are used to represent Boxes or blanks are used to represent orbitals.orbitals.
Arrows represent electrons.Arrows represent electrons. Upward-pointing arrows represent electrons with +1/2 spinUpward-pointing arrows represent electrons with +1/2 spin Downward-pointing arrows represent electrons with -1/2 spinDownward-pointing arrows represent electrons with -1/2 spin
Like EC but arrows are used instead of #’sLike EC but arrows are used instead of #’s
Orbital Filling DiagramsOrbital Filling Diagrams
Orbital Filling DiagramsOrbital Filling Diagrams
Rules to remember when writing an Rules to remember when writing an orbital filling diagram for a certain orbital filling diagram for a certain atom:atom:
Hund’s Rule – each orbital gets one electron before any get two EX: Nitrogen each 2p orbital gets on e-
before any get 2 e-.
Orbital Filling DiagramsOrbital Filling Diagrams
Hund’s Rule (cont.)Hund’s Rule (cont.)
Notice that the 2p electrons are shown as… Notice that the 2p electrons are shown as…
rather than. rather than.
This is WRONG!!!
Orbital Filling DiagramsOrbital Filling Diagrams
Rules to remember when writing an Rules to remember when writing an orbital filling diagram for a certain orbital filling diagram for a certain atom:atom:
Pauli Exclusion PrinciplePauli Exclusion Principle – electrons in – electrons in the same orbital must spin opposite the same orbital must spin opposite directions.directions. This is why one arrow is This is why one arrow is drawn updrawn up and one is and one is
drawn downdrawn down..
Orbital Filling DiagramsOrbital Filling DiagramsExamples of An Orbital Filling DiagramsExamples of An Orbital Filling Diagrams
OFD and ECOFD and EC
SummarySummary
Be able to…Be able to…
Explain what EC and OFD areExplain what EC and OFD are
Write and ECWrite and EC Recall the Auf Bau PrincipleRecall the Auf Bau Principle
Write and OFDWrite and OFD Recall Hund’s Rule Recall Hund’s Rule Recall the Pauli Exclusion PrincipleRecall the Pauli Exclusion Principle