1. Electron Configuration H & CP Chemistry Chapter 13

2. Quantum Mechanical Model (better than the Bohr Model) Bohr model describes electrons “in orbit” at different levels around the nucleus. Each level holds 2-8-8-18… electrons. Quantum model describes each individual electron in a specific configuration based on its energy.

3. What are electron configurations?  Electron Configurations regions of space where electrons are likely to be found, based on their energy.

4. United States of America

5. An electron configuration expresses: energy level or shell (the farther it is from the nucleus the more energy it has). A number 1 – 7.

6. 1 2 3 4 Electron energy levels or shells Electron energy levels or shells Shell number = Period number

7. An electron configuration expresses: energy level or shell (the farther it is from the nucleus the more energy it has). A number 1 – 7. sublevel or subshell ( shape of the region of space the electron occupies). A letter s, p, d or f.

8. Subshell or Sublevel - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy sublevel within the shell. - relative energy: s < p < d < f s subshell: spherical 1 orbital p subshell: pair of lobes x y z x y z

9. d subshellf subshell

10. 1 2 3 4 5 6 7 6 7 1A 2A 3B4B5B6B7B8B 1B2B 3A4A5A6A7A 8Agroup # = # valence (outside) e- d p f s Row = # shells

11. An electron configuration expresses: energy level or shell (the farther it is from the nucleus the more energy it has). A number 1 – 7. sublevel or subshell ( shape of the region of space the electron occupies). A letter s, p, d or f. orbital (specific region within the sublevel). Each orbital has room for up to 2 electrons.

12. Orbital refers to the specific area in which the electron can be located within a sublevel have equal relative energy within a sublevel s subshell: spherical 1 orbital p subshell: pair of lobes 3 orbitals x y z x y z

13. d subshell 5 orbitals f subshell 7 orbitals

14. An electron configuration expresses: energy level or shell (the farther it is from the nucleus the more energy it has). A number 1 – 7. sublevel or subshell ( shape of the region of space the electron occupies). A letter s, p, d or f. orbital (specific region within the sublevel). Each orbital has room for up to 2 electrons. direction the electron is spinning. Up or down.

15. How are electron configurations expressed? Electron configs can be: Written Drawn

16. Written Electron Configurations 1s 2 Energy Level Sublevel Number of electrons in the sublevel 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 … etc.

17. Drawn Electron configuration Drawn in order of increasing energy from bottom to top Energy level (number) and sublevel (letter) are written Boxes or lines represent orbitals represent electrons

18. Aufbau Principle Aufbau Principle: Electrons enter orbitals of lowest energy first, Be careful sometimes energy sublevels in the one energy level can overlap with the next energy level. represent electrons

19. LithiumLithium Atomic number = 3 1s 2 2s 1 ---> 3 total e - Group 1A Aufbau Diagram for Li

20. Hunds Rule When electrons occupy orbitals of equal energy, 1 electron enters each orbital until all orbitals are filled Fill out for Nitrogen – has 7 electrons!

21. CarbonCarbon Group 4A Atomic number = 6 1s 2 2s 2 2p 2 ---> 6 total e -

22. Pauli Exclusion Principle To occupy the same orbital electrons must spin in opposite directions

23. Summary s p d f # of Orbitals (shapes) Max # of Electrons in the Sublevel Starts at energy level 121 362 5103 7 14 4 Sublevel letter

24. Electronic Configuration according to Quantum Mechanics The location of an electron is described by 3 terms. 1 st Term: Shell (n) n = 1 n = 2 n = 3 lone electron of Hydrogen So we write 1s 1

25. The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom H 1s 1 He 1s 2 He 1s  1s1s **if there are 2 electrons in the same orbital they must have the opposite spin. (Pauli’s Exclusion Principle)

26. 1s1s The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2 nd shell (2)

27. 1s1s The Electronic Configuration of Boron & Carbon 2 nd shell 2s2s 2p2p 1s1s 2s2s 2p2p 2p  2s  B 1s  C = 1s 2 2s 2 2p 2 2p   2s  C 1s 

28. sources www.cast.uark.edu/.../USpop1990.html http://www.ccs.k12.in.us/chsBS/kons/kons/images/carbon.gif http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/qua ntum.html http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/qua ntum.html http://commons.wikimedia.org/wiki/File:F_orbital.png http://www.uh.edu/engines/heliumatom.jpg http://grandinetti.org/Teaching/Chem121/Lectures/MultiElectronA toms/assets/OrbitalEnergies.gif http://grandinetti.org/Teaching/Chem121/Lectures/MultiElectronA toms/assets/OrbitalEnergies.gif http://en.wikipedia.org/wiki/Exposure_(photography) http://en.wikipedia.org/wiki/Exposure_(photography