Electron Configurations

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Electron Configurations

• Today we are going to assign addresses to each
  electron.
• The energy diagram shows where we put the
  electrons in every atom
• BUT there are rules to putting in electrons

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Labeling of Electrons

• Electrons in atoms are arranged in the following
  order
• LEVELS
• SUBLEVELS (shape/type)
• ORBITALS (which specific orbital)

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Rearrange The Periodic Table
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Time to Color
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Labeling
1s
1s
2s 3s 4s 5s 6s 7s
2p 3p 4p 5p 6p
3d 4d 5d 6d
4f 5f
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How many electrons?
Find each orbital type on your energy diagram and
fill in the table below
s orbitals
d orbitals
p orbitals
f orbitals
Number of orbitals
1
3
5
7
Number of electrons
6
10
14
2
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Lithium

• Atomic number 3
• (Total of 3 electrons)

Starting at the bottom is the Aufbau
principle Electrons are represented with arrows,
but no two can be exactly the same. Therefore
one has a spin up, and one has a spin down, just
to differentiate between them This is the Pauli
Exclusion Principle
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Carbon

• Atomic number 6
• (Total of 6 electrons)

HUNDS RULE When placing electrons in a set of
orbitals having the same energy, we place them
singly as long as possible.
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Can you fill in the energy diagram for the
following atoms

• Al
• Ca
• Mn

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Box Diagrams
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Practice Box Diagrams
N
Ne
B
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Electron Configurations

• 2p2

Number of electrons in the orbital
Energy Level
Sublevel
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
4f14 etc.
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Electron Configurations

• A list of all the electrons in an atom (or ion)
• Must go in order (Aufbau principle)
• 2 electrons per orbital, maximum
• We need electron configurations so that we can
  determine the number valence electrons.
• The number of valence electrons determines how
  many and what this atom (or ion) can bond to in
  order to make a molecule

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
4f14 etc.
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Lets Try It!

• Write the electron configuration for the
  following elements
• H
• Li
• N
• Ne
• K
• Zn
• Pb

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Shorthand

• Write the electron configuration for Erbium

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
4f12
Replace With
The last filled Noble Gas. In this case, Xenon
Xe 6s2 4f12
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Write Shorthand

• Ca
• Sb
• W
• Mo
• Os
• Ra

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Ion Configurations

• To form anions from elements, add 1 or more e-
  from the highest sublevel.
• So, Phosphorus Ne 3s2 3p3 2e-
• will become P2- Ne 3s2 3p5

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Ion Electron Configuration

• S2-
• Mg2