Orbital Filling
Electron Configurations
Where do these electrons go?
Aufbau Principle
• Orbitals are filled from lowest energy to
highest energy
• Orbitals closest to the nucleus contain lower
energy
– They are filled first
Orbital Energies Lowest to Highest (p. 147)
Orbital Diagrams
• Shows the distribution of electrons within
orbitals
• Circles/Lines/Boxes are used to represent the
different orbitals
• Arrows are used to represent single electrons
Orbital Diagrams for …
• Hydrogen
• Helium
– Pauli Exclusion Principle
– Each orbital can only contain two electrons
– These electrons must be distinguished from one
another (“opposite spin”)
– One arrow up, One arrow down
• Lithium
Orbital Diagrams for…
• Boron
– The first “p” sublevel
– When the sublevels are drawn, all orbitals within
that sublevel must be drawn
• Carbon
– Hund’s Rule
– Electrons will not pair up within orbitals until each
orbital within a sublevel contains at least one
electron
– Electrons distribute “evenly”
Orbital Diagrams for …
• Neon
– All orbitals within the highest energy level are
completely filled
– These elements are chemically stable (“Noble
Gases”)
• Phosphorus
– Hund’s Rule
Orbital Diagrams for…
• Argon
– Completely filled energy level
• Potassium
– Aufbau Principle
• Lowest energy orbitals filled first
• 4s orbitals have lower energy that 3d
• They are filled first
Orbital Diagrams for…
• Manganese
– Aufbau Principle
• Lowest energy orbitals filled first
• 3d orbitals have higher energy that 4s, but lower than 4p
– Hund’s Rule
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•
•
•
Hund’s Rule applies to all sublevels
There are five “d” orbitals
Each one will receive one electron before any are paired
There are exceptions to this rule within transition metals,
but the concept is applied here for practice
Electron Configurations
• A short hand way of representing the
“location” of electrons around the nucleus
• Not as much detail as orbital diagrams, but a
convenient way of showing patterns for
groups of elements on the periodic table
Electron Configurations for…
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•
•
•
•
•
•
Hydrogen
Helium
Lithium
Boron
Carbon
Neon
Sodium
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Phosphorus
Argon
Potassium
Manganese
Patterns in Electron Configurations
• All elements within the same column have the
same “ending” for their electron configuration
– All end with electrons in the same sublevel, but
different principle energy level
• These elements all belong to the same
“family” or “group”
• They exhibit similar chemical properties
– Due to their similar electron configurations, which
will be discussed in more detail in later chapters
Groups of Elements & Electron
Configurations