Download Electron Configuration–Honors

How are electrons
distributed in an atom?
Electron Configuration
 Shorthand method for representing electrons’
distribution in orbitals within subshells
 All orbitals have the same energy level—digenerate
 Orbitals– mathematical expressions of probability of
electron’s location
 Electrons occupy orbitals in a way that gives LOWEST
energy state
Aufbau Principle
 Electrons occupy the LOWEST energy orbital
available
 Lazy Hogs !
Hund’s Rules
 Developed by Friedrich Hund
 Creates the most stable electron arrangement
 Based on electron spin
Hund’s Rules cont.
1) One electron MUST occupy each orbital BEFORE
electrons are paired in the same orbital.
2) Electrons added to subshell with the same spin (+1/2,
-1/2) so each orbital has one electron.
Pauli Exclusion Principle
 Only 2 electrons occupy each orbital
 Electron spins MUST be opposite/paired when 2
electrons occupy the same orbital
 +1/2, -1/2

Using the periodic table- Period numbers = principal quantum number of
valence shell electrons
 Subshells fill with electrons at different regions within
periodic table (s section, p section)
Ex. 1 Nitrogen
Ex. 2 Cr
Orbital Diagrams
 Visual representation of electron configuration
 Represents electrons’ spins (, )
Ex. 3 Mg
Ex. 4 Sn
Practice
1) Boron
6) Mn
2) Copper
7) O
3) Sodium
8) Li
4) Ca
5) Br