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1 Title and Highlight Topic: EQ: Date Reflect Question: Reflect on the material by asking a question (its not suppose to be answered from notes) NOTES: Write out the notes from my website. Use different types of note-taking methods to help you recall info (different color pens/highlighters, bullets, etc) When I lecture we will add more info, so leave spaces in your notes DRAW ANY PICTURES, FIGURES, AND WRITE OUT ANY PRACTICE PROBLEMS/QUESTIONS. WE WILL ANSWER THEM TOGETHER. So LEAVE SPACES SO WE CAN ANSWER QUES. Summary (end of notes) : 1-2 Sentences of what you learned

2 Niels Bohr Developed a Simple Model to Explain These Results Draw with notes

3 The Energy Is Quantized Draw with notes The energy of each Bohr orbit, specified by a quantum number n = 1, 2, 3 is fixed, or quantized. Bohr orbits are like steps of a ladder, each at a specific distance from the nucleus and each at a specific energy.

4 Excitation and Emission When a hydrogen atom absorbs energy, an electron is excited to a higher-energy orbit. The electron then relaxes back to a lower-energy orbit, emitting a photon of light. Draw with notes

5 The Bohr Model: Atoms with Orbits Bohr model - predicted the lines of the hydrogen emission spectrum. However, it failed to predict the emission spectra of other elements that contained more than one electron. Bohr model was replaced with the quantum-mechanical or wave-mechanical model.

6 In the quantum-mechanical model, Bohr orbits are replaced with quantummechanical orbitals. Orbitals are different from orbits - they represent probability maps that show a where the electron is likely to be found.

7 Quantum Mechanics Electrons do not behave like particles flying through space. Orbital ( electron cloud ) Region in space where there is 90% probability of finding an electron 90% probability of finding the electron Orbital The greater dot density near the middle represents a higher probability of finding the electron near the nucleus. Draw with notes Courtesy Christy Johannesson

8 Electron capacities Copyright 2006 Pearson Benjamin Cummings. All rights reserved.

9 Principal Quantum Numbers for Orbitals The lowest-energy orbital 1s orbital. Number = 1 and the letter = s (shape of orbital). The number is called the principal quantum number (n) and specifies the principal shell of the orbital. n can range from n=1.7 (why? Because there are 7 periods)

10 Ground States and Excited States ground state - lowest energy state When the e- is in a higher-energy orbital, the hydrogen atom is said to be in an excited state.

11 Energy Increases with Principal Quantum Number The higher the principal quantum number (n), the higher the energy (E) of the orbital. (direct relationship) The possible principal quantum numbers are n = 1, 2, 3, etc to 7 Since the 1s orbital has the lowest possible n, it is in the lowest-energy shell and has the lowest possible E. Draw with notes

12 Shapes of Orbitals The letter indicates the subshell of the orbital and specifies its shape. The possible letters are s, p, d, and f, each with a different shape. Orbitals can be drawn as geometric shapes Will study more in CH 1

13 The s Orbitals: called spheres There are one s orbitals Draw with notes The 2s Orbital Is Similar to the 1s Orbital, but Larger in Size

14 The p Orbitals: called dumbbells There are three p orbitals Draw with notes

15 The d Orbitals: called clovers There are five d orbitals Draw with notes

16 Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

17 Copyright 2006 Pearson Benjamin Cummings. All rights reserved.

18 General Rules Pauli Exclusion Principle Each orbital can hold TWO electrons with opposite spins. Wolfgang Pauli Draw with notes Electron spins = arrows in opposite direction Orbital diagram (box) Courtesy Christy Johannesson

19 Energy General Rules Aufbau Principle Electrons fill the lowest energy orbitals first. 6d 5f 7s 6p 5d 4f 6s 5p 4d 5s 4p 3d 4s 3p 7s 6s 5s 4s 6p 5p 4p 6d 5d 4d 3d 5f 4f 3s 3p 3s 2p 2s 2p 2s 1s 1s Don t Draw Courtesy Christy Johannesson

20 General Rules Hund s Rule Draw with notes Within a sublevel, place one electron per orbital before pairing them. Empty Bus Seat Rule WRONG RIGHT Courtesy Christy Johannesson

21 Electron Filling in Periodic Table s s 1 p 2 3 d f

22 Label the top of the groups on your PT s 1 Elements in the s - blocks s 2 s 2 He

23 Label the top of the groups on your PT The P-block p 1 p 2 p 3 p 4 p 5 p 6

24 Draw LEFT side Maximum of Electrons In Each Sublevel Maximum Number of Electrons In Each Sublevel Maximum Number Sublevel Number of Orbitals of Electrons s 1 2 p 3 6 d 5 10 f 7 14 LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World, 1996, page 146

25 Principal Quantum Number ( n ) Draw with notes Energy level 1s Size of the orbital PERIOD # (except Transition/Inner Tran s Metals) 2s 3s Courtesy Christy Johannesson

26 Electron Configurations: How Electrons Occupy Orbitals An electron configuration (e.c.) shows the location of every orbital, # of e- in each orbital for a particular atom. The e.c. formula is the following: nl # Valence e- = outer most electrons PQ# = period # Orbital shape = s, p, d, f

27 Periodic Patterns Example - Hydrogen s 1 # of valence electrons 1st Period s-block Courtesy Christy Johannesson

28 Electron Configurations: Orbital Diagrams The orbital diagram for a ground-state hydrogen atom is as follows: The box represents the 1s orbital, and the arrow within the box represents the electron in the 1s orbital.

29 Let s Practice The following slides we will do in class!! Don t write them in notes yet Get out PT List the first 18 elements (symbols) Leave space between each element.

30 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + OK, so we re going to use arrows pointing up or down to represent the electrons. Can you guess into which box the first electron would go given that it is attracted to the nucleus?

31 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 1 That s right: it goes in the 1s sublevel. And its el. config is 1s 2. Notice in the table above where H is in the area designated as 1s. So where does the next electron go?

32 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 If you were thinking it went in the 2s, then you forgot that each orbital can hold up to two electrons. Note how He is right here in the area designated as 1s 2 and so its el. config. is 1s 2.

33 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 1 Now that the 1s is filled, the next electron goes in the next sublevel the 2s. Again note how Li is in 2s 1. Its full el. conf. is 1s 2 2s 1. What is Be s el. conf?

34 Arbitrary Energy Scale Energy Level Diagram 6s 6p 5d 4f Lithium 5s 5p 4d Bohr Model 4s 4p 3d 3s 3p N 2s 2p 1s NUCLEUS H He Li C N Al Ar F CLICK ON ELEMENT TO FILL IN CHARTS Fe La Electron Configuration Li = 1s 2 2s 1

35 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 Is this what you were thinking? Good. Now look at the periodic table above, what comes after the 2s sublevel? The 2p sublevel. So what will the next el. conf. be?

36 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 1 Is this what you were thinking? Notice how B is in the 2p 1 spot. So its full el. conf. is 1s 2 2s 2 2p 1. What s next?

37 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 2 Is this what you were thinking? Notice how C is in the 2p 2 spot. So its el. conf. is 1s 2 2s 2 2p 2 Notice also how when we fill a sublevel

38 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 3 we put one electron in each orbital until the sublevel is half filled

39 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 4 and then we go back and start pairing off This is called Hund s Rule, but it also referred to as the bus seat rule. Can you figure out why?

40 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 5 Look at F. It s just one electron away from having filled 2p sublevel And it s just one square away from the end of the 2p block.

41 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 And then Ne has a completely filled outer level. Na is next. Can you guess where the next electron is going to go?

42 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 1 That s right: in the 3s sublevel. Right now, write down in your notebook what you think the next three el configs will be.

43 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 Did you get this one right?

44 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 1 How about Al s? See how Al is in the 3p 1 spot on the per table and its el config ends with 3p 1

45 Arbitrary Energy Scale Energy Level Diagram 6s 6p 5d 4f Aluminum 5s 5p 4d Bohr Model 4s 4p 3d 3s 3p N 2s 2p 1s NUCLEUS H He Li C N Al Ar F CLICK ON ELEMENT TO FILL IN CHARTS Fe La Electron Configuration Al = 1s 2 2s 2 2p 6 3s 2 3p 1

46 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 2 Now just advance through the next 23 slides, but as you do, make sure you are understanding

47 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 3 Exactly what is going on how the el configs simply follow the sequence of the periodic table.

48 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 4 Your goal by the end of this slide show is to be able to write el configs for any element using just the periodic table and your brain!

49 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 5

50 5s 4d 4p 4s 3s 2s 3p 2p s 1 2 3d d f p s + 1s 2 2s 2 2p 6 3s 2 3p 6

51 Ch 9.7: Core and Valence Electrons Core electrons: Inside Electrons closet to nucleus Valence Electrons: electrons in the - outer most energy level (or shell). (MOST IMPORTANT FOR BONDING!!) V.E. = s electrons and p electrons only. (V.E. = A Groups only on PT ) Counting Valence Electrons MAXIMUM NUMBER OF VALENCE ELECTRONS = 8 e- (only exception Helium = 2 e - s) Examples: Ca = 2 e - s Nitrogen = 5 e - 8 s Argon = e - s d-block and f-block = 2 or 1 valence e - s

52 Electron Configurations and the Periodic Table The elements within A groups (not B groups) of the P.T. all have the same number of v.e. and similar outer e.c. With notes - Make a sketch with boxes. Label symbols and label A groups

53 Valence Electrons and Core Electrons What is e.c. for Si? Silicon has 4 v.e. (those in the n = 3 principal shell) and 10 core electrons. Draw with notes

54 Valence Electrons and Core Electrons What is e.c. for Se? Selenium has 6 v.e. (those in the n = 4 principal shell). Draw with notes All other electrons, including those in the 3d orbitals, are core electrons.

55 Periodic Trends in Electron Configurations of the Transition Series Elements The transition metals ( B groups) have e.c. differ from A group elements. For the 1 st row of trans. metals (in period 4), they all have the outer configuration of 4s 2 3d x (x = number of d electrons). So, valence e- are always 2 (or sometimes 1 for two special groups in the d-block hint, hint)!!

56 Periodic Trends in Electron Configurations of the Transition Series Elements Two exceptions groups: Cr is 4s 1 3d 5 and Cu is 4s 1 3d 10. So, valence e- will be 1!! (only for those 2 groups in d-block) (2e ) for 4s 2 3d x (1e ) for 4s 1 3d 5 or 4s 1 3d 10

57 Noble Gas Configuration Draw with notes [Ne] 3s 1 A B C D neon's e.c. (1s 2 2s 2 2p 6 ) third energy level one electron in the s orbital orbital shape Na = [1s 2 2s 2 2p 6 ] 3s 1 electron configuration

58 Noble Gas Electron Configuration Example - Germanium Ge [Ar] 4s 2 3d 10 4p 2 Courtesy Christy Johannesson

59 Notation 16 S Longhand Configuration S 16e - 1s 2 2s 2 2p 6 3s 2 3p 4 Core Electrons Valence Electrons Noble Gas (Shorthand) Configuration S 16e - [Ne] 3s 2 3p 4 Courtesy Christy Johannesson

60 LEFT side Practice Element symbol V Ag I Sg Electron configuration [Ar] 4s 2 [He] 2s 2 2p 5 [Kr] 5s 2 4d 10 5p 6 [Ar] 4s 2 3d 6 Valence e-