1. Electron Configuration  More complex than simple concentric circles.

2. Orbit vs. orbital?? -orbit the path an electron takes (Bohr) -orbital a region around the nucleus where an electron with a given energy is likely to be found

3. Orbitals and energy -each principle energy level is divided into one or more sublevels n=1 has one sublevel n=2 has two sublevels n=3 has three sublevels

4. Orbital Representations  Four basic orbital shapesThe s orbitals are spherical: 1s 2s 3s

5. p Orbitals: “peanut”  Have two lobes lying along the x, y, or z axis.  Different orientations labelled p x, p y, and p z.

6. Sodium Diagram

7. d Orbitals: “double p” Have complicated shapes, but the electron density at the nucleus is always zero.

8. f Orbitals  orbital shape highly varied  high energy electrons

10. How do energy levels, sublevels, and orbitals fit together?

11. Orbitals and energy -principle energy levels proposed by Bohr (n) n=1 n=2 n=3

12. Orbitals and energy (cont’d) - there may be only one of each type of sublevel at each energy level - each sublevel consists of one or more orbitals spdfspdf Increasing energy 13571357

13. Orbitals and energy (cont’d) -sublevels are written with the quantum number and the type of orbitals 1s1s2p2p energy leveltype of orbital

14. 1 st principle energy level (n=1) -since n=1, there is only one sublevel 1s1s -the s sublevel only consists of one orbital -there is only 1 orbital in this energy level

15. 2 nd principle energy level (n=2) -since n=2, there are two sublevels 2s2p2s2p -there is one s orbital in the 2s sublevel and three p orbitals in the 2p sublevel -4 total orbitals in this energy level

16. 3 rd principle energy level (n=3) -since n=3, there are three sublevels 3s3p3d3s3p3d -there is 1 s orbital, 3 p orbitals, and 5 d orbitals -9 total orbitals in this energy level

17. 4 th principle energy level (n=4) How many sublevels? 4 Name the sublevels.4s4p4d4f4s4p4d4f How many total orbitals? 16

18. Orbitals and energy (cont’d) How does a 1s orbital differ from a 2s orbital? How does a 2p orbital differ from a 3p orbital? SIZE & ENERGY

19. Electron spin -electrons behave as though they were spinning on their own axis, creating a magnetic field -2 “types” of spin clockwise counterclockwise

20. Electron spin (cont’d) -if 2 electrons have opposite spins, they cancel each other out -if 2 electrons have parallel spins, there is a net effect on the magnetic field -each orbital can hold a maximum of 2 electrons

21. Electron spin (cont’d) sublevel # of orbitals max. # e - s12 p36 d510 f714

22. Remember Bohr’s atom (2n 2 )? n=1 n=2 n=3 Level (n) sublevels orbitals max. # e - 1 1 (s)(s)12 2 2 (s, p)p)48 3 3 (s, p, d)d)918 4 4 (s, p, d, f)f)1632

23. Writing electron configurations An electron configuration shows the distribution of electrons among orbitals in an atom (location, energy). Why is it important? -the behavior of atoms is determined by the outer electrons (bonding)

24. Electron configuration (cont’d) When writing electron configurations, you must obey three rules: 1. The Aufbau Principle 2. The Pauli Exclusion Principle 3. Hund’s Rule

25. The Aufbau Principle -electrons are added one at a time to the lowest energy levels until all electrons of the atom have been accounted for

26. Aufbau Principle (cont’d) 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f

27. The Pauli Exclusion Principle -an orbital can hold a maximum of 2 electrons -the e - must have opposite spins -termed “paired” and “unpaired”

28. Hund’s Rule -electrons occupy equal energy orbitals so that a maximum number of unpaired electrons results -in a sublevel, you place one e - in each orbital first, the go back and pair them up

29. Example lithium 3e - 1s1s 2e - 1e - 2s2s orbital diagram e - configuration 1s22s11s22s1

30. Example oxygen 8e - 7e - 6e - 5e - 4e - 3e - 2e - 1e - 1s1s2s2s2p2p 1s22s22p41s22s22p4

31. Practice Problem Write the orbital diagram and electron configuration for sodium. 1s1s2s2s2p2p 3s3s 1s22s22p63s11s22s22p63s1

32. Practice Problem Write the orbital diagram and electron configuration for nickel. 1s1s2s2s2p2p3s3s3p3p4s4s3d3d 1s22s22p63s23p64s23d81s22s22p63s23p64s23d8

33. H 1s1H 1s1 He 1s 2 fullNoble gas Li 1s 2,2s 1 Be 1s 2,2s 2 B 1s 2,2s 2 p 1 C 1s 2,2s 2 p 2 N 1s 2,2s 2 p 3 O 1s 2,2s 2 p 4 F 1s 2,2s 2 p 5 Ne 1s 2,2s 2 p 6 fullNoble gas Yellow Valence Electrons in Yellow

34. Electron Configurations and the Periodic Table Write electron configurations for: 13 Al: [Ne] 3s 2 3p 1 1s 2 2s 2 2p 6 3s 2 3p 1 50 Sn:[Kr] 5s 2 4d 10 5p 2 82 Pb +2 : [Xe] 6s 2 4f 14 5d 10 92 U: [Rn] 7s 2 6d 1 5f 3 26 Fe: [Ar] 4s 2 3d 6 [Ar] 4s 3d