1. To Do 6 th HW assignment due Wednesday, March 18, by 10 pm. Exam 2: Thursday, March 19, 7:00 pm. Sign up for conflict in 367 Noyes Lab. 1

2. Quantum Numbers 2

3. A Comparison of the Radial Probability Distributions of the 2s and 2p Orbitals 3

4. A Comparison of the Probability Distributions of the 2s and 2p Orbitals 4

5. Radial Probability (3s, 3p, 3d) 5

6. Orbital Energy Levels for the Hydrogen Atom 6

7. The Orders of the Energies of the Orbitals in the First Three Levels of Polyelectronic Atoms 7

8. Electron Configurations for First 18 Elements 8

9. The Orbitals Being Filled for Elements in Various Parts of the Periodic Table 9

10. Valence Electrons Highest or outermost energy level electrons Where the chemistry “happens”! Look at principal quantum level n Sulfur: 1s 2 2s 2 2p 6 3s 2 3p 4 Valence electrons are in n = 3 level Valence electrons = 2 + 4 = 6 electrons 10

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12. Clicker Question How many unpaired electrons does sulfur contain in its ground state? (Hint: Draw an orbital diagram.) A)0 B)1 C)2 D)3 E)6 12

13. Clicker Question Which of the following (a-c) does not correctly match the species with the expected electron configuration? a)A ground state calcium atom[Ar] 4s 2 b)The most stable ion for bromine[Ar] 4s 2 3d 10 4p 6 c)An excited state of sulfur[Ne] 3s 2 3p 3 4s 1 d)At least two of the above (a-c) are incorrectly matched. e)All of the above (a-c) are correctly matched. 13

14. Atomic Radius (Size) Generally increases down a group Hydrogen INCREASES! Francium Orbitals are getting larger and electrons fill further and further from the nucleus at higher energy levels 14

15. Atomic Radius (Size) Generally decreases across a row (period) – outer electrons in the same energy level Hydrogen Fluorine DECREASES! More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly, pulling them in and shrinking the size. 15

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17. Energy REQUIRED to remove an electron 17

18. Ionization Energy Generally decreases down a group Hydrogen DECREASES! Francium Orbitals are getting larger and electrons fill further and further from the nucleus at higher energy levels. Electrons are not as tightly bound by the nucleus at higher energy levels so it takes less energy to remove an outer electron. 18

19. Ionization Energy Generally increases across a row (period) – outer electrons in the same energy level Hydrogen Fluorine INCREASES! More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly and pulling them in closer to the nucleus, requiring MORE energy to remove an outer electron. 19

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21. Elements/Ions Do Not “Want” To Lose Electrons! 21

22. Clicker Question Rank the following from smallest to largest atomic radius. a)Rb, Ca, Br, N b) Br, N, Rb, Ca c) N, Rb, Br, Ca d)N, Br, Ca, Rb e)Ca, Rb, N, Br 22

23. Clicker Question Rank the following from smallest to greatest ionization energy. a)Rb, Ca, Br, N b) Br, N, Rb, Ca c) N, Rb, Br, Ca d)N, Br, Ca, Rb e)Ca, Rb, N, Br 23