1. Electron Configurations distributedExplains how electrons are distributed among an atom’s orbitals address,Each part identifies part of an electron’s “address,” or location,within an atom Example: 1s 2 is the electron configuration for helium 1 electrons - 1 is the highest energy level helium in which He places electrons in the ground state stype - s is the type of orbital in which the electrons are being placed (called sublevels) 2 number - 2 is the number of electrons found in that orbital

2. Principal Energy Levels 7 period7 principal energy levels - one correlating to each period (row) on the periodic table increaseEach level requires an increase in energy for electrons to be placed there

3. sublevelsshapeeach principal energy level has its own number of sublevels (describes shape of orbitals) Sublevels - s sublevel: spherical (groups 1 and 2) - p sublevels: dumbbells (groups 13 - 18) - d sublevels (transition metals) - f sublevels (lanthanides & actinides)

4. Atomic Orbitals

5. Each sublevel contains a different number of orbitals Orbitals are r rr regions where electrons are most l ll likely to be found in an atom s1 - s sublevel has 1 orbital p3 - p sublevel has 3 orbitals d5 - d sublevel has 5 orbitals f7 - f sublevel has 7 orbitals

6. Atomic Orbitals Each orbital holds only 2 electrons

7. Electron Configuration Rules Aufbau’s rule: electrons are placed in orbitals of lowest energy first - ground state: lowest energy level occupied by an electron - excited state: any level above the ground state in which an atom’s electron is found Hund’s rule: when electrons enter orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with the same spin Pauli’s exclusion principle: each orbital can hold a maximum of two electrons with opposite spin

9. Sublevels & Periodic Table

10. Valence Electrons group - elements in the same group react in a similar manner valence -they share similar reactions because they have the same number of valence electrons outermost - valence electrons are the electrons in the outermost energy level

11. Atom/ Ion Orbital Diagram Electron Configuration H 1 electron 1s 1s 1 1 UPE1 VE

12. Atom/ Ion Orbital Diagram Electron Configuration Be 4 electrons 1s 1s 2 2s 2 2s 0 UPE2 VE

13. Atom/ Ion Orbital Diagram Electron Configuration B 5 electrons 1s 1s 2 2s 2 2p 1 2s2p 1 UPE3 VE’s

14. Atom/ Ion Orbital Diagram Electron Configuration O 8 electrons 1s 1s 2 2s 2 2p 4 2s2p 2 UPE’s6 VE’s

15. Atom/ Ion Orbital Diagram Electron Configuration Ne 10 electrons 1s 1s 2 2s 2 2p 6 2s2p 0 UPE’s8 VE’s

16. Atom/ Ion Orbital Diagram Electron Configuration Mg 12 electrons 1s 1s 2 2s 2 2p 6 3s 2 2s2p3s 0 UPE2 VE

17. Atom/ Ion Orbital Diagram Electron Configuration Cl 17 electrons 1s 1s 2 2s 2 2p 6 3s 2 3p 5 2s2p3s 1 UPE 7 VE 3p

18. How many electrons can be placed into the 2p orbitals? A.6 B.2 C.4 D.8

19. How many electrons can be placed in the third energy level? A.6 B.10 C.18 D.24

20. How many sublevels are there in the fourth energy level? A.2 B.3 C.5 D.7

21. How many electrons can be placed in the 4f sublevel? A.6 B.2 C.10 D.14

24. Noble Gas Shortcut The Noble Gas shortcut can be used to represent the electron configuration for atoms with many electrons. Noble gases have a full s and p and therefore can be used to represent the inner shell electrons of larger atoms. Lead: Write the electron configuration for Xenon: Substitution can be used: Manganese Arsenic Promethium

25. Ion Charges Metals lose electrons (forming cations) in order to have the same electron configuration as the nearest noble gas (very stable; typically 8 valence electrons Nonmetals gain electrons (forming anions) in order to have the same electron configuration as the nearest noble gas

27. Group General Electron Configuration Number of Valence Electrons in Atom Charge 1 (alkali metals)s1s1 2 (alkaline earth metals) s2s2 13s2p1s2p1 14s2p2s2p2 15s2p3s2p3 16s2p4s2p4 17 (halogens)s2p5s2p5 18 (noble gases) s2p6s2p6 1 +1 2 +2 3 +3 (Al, Ga) 4 -4 5 -3 6 -2 7 2 (He) 8 (all others) 0

28. What charge would an aluminum (Al) ion have? A.+1 B. +3 C. -3 D. -5 What charge would an iodine (I) ion have? A.+1 B. -2 C. -1 D. 0 What charge would a strontium (Sr) ion have? A.+1 B. +3 C. -3 D. -5 What charge would a nitrogen (N) ion have? A. +1 B. +3 C. -3 D. +5