4.3 electron configurations
• Aufbau principle- an electron occupies the
lowest – energy level that can receive it.
• Hunds Rule – orbitals of equal energy are
each occupied by one electron, (all the
electrons have the same spin), before any
orbital is occupied by a second electron
having an opposite spin
Review
• Pauli exclusion principle- no two electrons can have the same set of
quantum numbers.
• Introduction clip
Orbital boxes
Do the orbital boxes for
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B
N
Cl
Ca
Mn
Se
Rb
Ag
Electron configuration
• Description of the arrangement of an atom’s
electrons.
Highest occupied level
• The highest principle quantum level that
contains electrons.
• Example: determine the highest occupied
energy level for Al, and Cd
– Third energy level n=3
– Fifth energy level n=5
Inner shell electrons
• Electrons that are not in the highest energy
level.
Nobel gas configurations
• Short hand
• Family 18 are the Noble gases,
• They have a full outer level.
• Put the nearest, and lowest, Noble gas in
brackets and continue the configurations
from there.
• Page 111
Octet
• Filled s and p sublevels,
• A total of 8 electrons in the outer most
energy level. ( highest main energy level).
• Seen in the Noble gases.
• Exception He, has a filled 1s sublevel.
Orbital notation
Blanks with arrows on it, used like the orbital boxes, they are
all on one line.
Summary clip