Electron Location: Part III

1. Electron Location: Part III Electron Configuration

4. 4f 4d 4p 4s 14(7) 10(5) = sub-level = max. # of electrons = # of electrons = number of orbitals 6(3) 32 2 (1) 3d 3p 3s 10(5) 6(3) 2(1) 18 2p 2s 6(3) 2(1) 8 1s 2(1) 2

8. Principal Energy Levels

9. “Rules” for Writing Electron Configurations • a method of writing where electrons are found in various orbitals around the nulcei of atoms. • three rules in order to determine this: • aufbau principle • Pauli exclusion principle • Hund’s rule

10. Aufbau Principle • electrons occupy the orbitals of the lowest energy first • each written represents an atomic orbital (such as or or or ….) • electrons in the same sublevel have equal energy ( ) • principle energy levels (1,2,3,4..) can overlap one another • ex: 4s orbital has less energy than a 3d orbital

11. “know” these two exceptions to the Aufbau principle!  (There are many others at the bottom of the table that we won't memorize)

12. Pauli Exclusion Priciple • only two electrons in an orbital • must have opposite spins • represents one electron • represents two electrons in an orbital

13. Hund’s Rules every orbital in a subshell must have one electron before any one orbital has two electrons all electrons in singly occupied orbitals have the same spin.

18. Order of Electrons 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

25. Writing Electron Configurations • To write out the electron configuration of an atom: • use the principal quantum number/energy level (1,2,3, or 4…) • use the letter term for each sub-level (s,p,d, or f); • use a superscript number indicates how many electrons are present in each sub-level • hydrogen =1s1. • Lithium =1s22s1. • don’t write anything for spin (yet)

29. Orbital Energy Diagrams Carbon Atomic # - 6 http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg

30. Orbital Energy Diagrams Neon Atomic # - 10 http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg

31. Orbital Energy Diagrams Scandium Atomic # - 21 http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg