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Orbitals, Electron Configurations

orbitals  

  • s orbital - lowest energy orbital, has spherical symmetry
    • y2 approaches 0 as it gets farther apart from nucleus
    • nodes - regions where y2 goes to 0
    • orbital size increases as n increases
  • p orbital - has dumbbell shaped orbital w/ 2 lobes
    • shape shows average distribution of electrons, not its path
    • every shell beyond the 1st has 3 p orbitals, each w/ different spatial orientation
  • d orbital - occur beyond 1st 2 shells
    • 5 different d orbitals
  • f orbital - occur beyond 1st 3 shells
    • 7 different f orbitals
  • in atoms w/ multiple electrons, repulsions cause different subshells to be at different energies
  • degenerate orbitals - orbitals w/ same energy

Pauli exlusion principle - no 2 electrons can have same set of quantum numbers (n, l, ml, ms)  

  • electron spin - property of electrons where each electron spins on an axis
  • spin generates magnetic field
  • ms = +1/2 or -1/2, spin magnetic quantum number
  • each orbital can hold 2 electrons, as long as they spin in opposite directions

Hund's rule - in degenerate orbitals, lowest energy obtained if max # of electrons have same spin  

  • electrons w/ same spin magnetic quantum number have parallel spins
  • electrons naturally repel one another, tend to occupy different orbitals if they can

electron configuration - way electrons are distributed among atoms' orbitals  

  • ground state - electrons in lowest possibly energy states
  • orbitals filled in order of increasing energy (max 2 electrons per orbital)
  • electrons w/ opposite spins are paired when in same orbital, unpaired electrons do not have an electron w/ opposite spin in same orbital
  • condensed electron configuration - abbreviated electron configuration
    • aka noble gas notation
    • electron configuration of nearest noble gas w/ lower atomic number represented by chemical symbol in brackets
    • only outer electrons matter in reactions
    • core electrons - inner-shell electrons
    • valence electrons - electrons given after noble gas core
  • lanthanide (rare earth) elements - fill up the 4f orbitals
  • actinide elements - fill up the 5f orbitals
  • representative (main-group) elements - in s and p blocks of periodic table

 

  • potassium (K) >> 1s22s22p63s23p64s1 or [Ar]4s1
  • iron (Fe) >> 1s22s22p63s23p64s23d6 or [Ar]4s23d6
Subject: 
Chemistry
Subject X2: 
Chemistry

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