Electron Distribution
LEQs
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How do electron configurations and the four quantum
numbers illustrate electron placement using the quantum
model?
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Electrons are located in energy levels which are
subdivided into sublevels and orbitals
Energy Levels(n): 1 through 7
Electrons held= 2n2
Sublevels:
s: 1 orbital: holds up to 2 electrons
p: 3 orbitals: holds up to 6 electrons
d: 5 orbitals: holds up to 10 electrons
f: 7 orbitals: holds up to 14 electrons
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Order
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1s2s2p3s3p4s3d4p5s4d5p6s4f5d6p7s5f6d7p
Rules
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Aufbau Principle: electrons fill lower energy levels before
filling higher energy levels
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Hund’s Rule: electrons in a sublevel will fill each orbital
before pairing up.
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Pauli’s Exclusion Principle: electrons in the same orbital
will have different spins
Orbital Notation
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Graphically represents the distribution of electrons.
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Steps:
1. Determine number of electrons to be distributed.
2. Determine the ending sublevel/orbital for the atom.
3. Draw boxes, circles, or lines to represent the orbitals.
4. Draw arrows (up or down) to represent the electrons.
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Ex: Magnesium
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Ex: Sulfur
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Ex: Nitrogen
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Ex: Iron
Electron Configuration
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“Shorthand” for orbital notation
Steps:
1. Determine the number of electrons
2. Determine the ending energy level/sublevel
3. Write out order until the ending sublevel
4. Represent electrons as exponents
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Ex: Potassium
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Ex: Scandium (Sc)
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Ex: Neon
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Ex: Zirconium (Zr)
Noble Gas Electron Configuration
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Shortened version of electron configuration
Steps:
1. Determine the number of electrons and ending energy
level/sublevel.
2. Determine the nearest noble gas with LESS electrons
3. Write the noble gas in brackets
4. Write the rest of the electron configuration using
exponents for electrons.
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Ex: Rubidium
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Ex: Tin
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Ex: Sodium
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Ex: Niobium (Nb)