1. Quantum model of an Atom Chapter 17

2. I read Chapter 15 before coming to class 1. Yes, the whole thing. 2. Nope, essentially none. 3. Well some, more than ½. 4. A little only. 0 of 250 10

3. The wave nature of moving particles is interpreted as being 1. An up and down path that the particle travels in as it moves. 2. A back and forth path that the particle travels in as it moves. 3. Not a traditional wave at all but instead is a function that tells us the probability of detecting the particle. 0 250

4. Perspective largesmall fast slow Newton’s Laws ok Relativity Wave-Particle Duality

5. Standing waves are created when 1. Waves reflect and bounce back to where they started from. 2. Waves wrap around and come back to where they started from. 3. Both 1 and 2 are ways standing waves can be created. 10 0 250

6. Standing Waves

7. 2 Dimensions  It is easy to create standing waves in 2 dimensions as well. A single wave on a drum head Two waves on a drum head Three waves on a drum head

8. 3 Dimensions  Standing waves can be set up inside the cavities of musical instruments as well. The patterns trace the nodes and antinodes on the violin sides.

9. Wrap standing waves around a point  These are patterns of vibration.

10. Bohr Model Explained!  Take de Broglie’s waves and wrap them in a standing wave pattern around the nucleus.  Put one wave, then two waves, then three waves, etc and you exactly predict the location of the Bohr radii! A CRUDE representation!

11. The Quantum Model of the Atom  Electrons are found in 3-D electron probability waves.  They do not orbit. Instead they exist in the locations given by standing wave clouds.  We call these wave clouds orbitals to reflect the fact that the electrons do not orbit like a planet.

12. Three Dimensional Atomic Orbitals  The shape and energies of the actual orbitals depend on the number of standing waves in the pattern. They are found from solving the Shrödinger Wave equation: h 2 d 2 (x) 8  2 m dx 2 + V(x)  (x) = E  (x) Kinetic Energy + Potential Energy = Total Energy

13. Orbital Patterns  One wave: Electrons will resonate in one pattern, called an “s” orbital.  Two waves: Electrons will resonate in two patterns, “s” and “p” orbitals s p s

14. Orbital Patterns  Three waves: Electrons will resonate in “s”, “p” and “d” orbitals. s p d One orbital

15. S Orbitals  All numbers of standing waves have “s” orbitals.  They are all round but their interiors are different.  Still, in each case there is just one orbital.

16. P Orbital  P orbitals come in sets of 3, whether there are 2 waves or 3 waves or more.

17. D Orbitals  D orbitals come in sets of 5, whether there are 3 waves or 4 waves or more.

18. Orbital Patterns  The pattern continues on as s, p, d, f, g, h, i, j, etc. Each new orbital set has two more orbitals than the previous one. Orbital Typespdfghij Orbitals in set13579111315 Standing Waves1234 Orbital Typesss,ps,p,ds,p,d,f Total Orbitals14916

19. The Pauli Exclusion Principle  At most two electrons can occupy the same orbital. If two electrons are in the same orbital, they must have different spins. e- e- Spin Down Spin Up Orbital Typespdfghij Orbitals in set13579111315 Electrons26101418222630

20. Understanding Atoms  How do electrons fill the orbitals as we move along the periodic table?  Electrons fill the lowest energy levels first. For the lighter atoms, fewer standing waves and simpler orbitals usually means lower energies.  From here on I’ll refer to number of standing waves (physics lingo) as energy levels or shells (chemistry lingo). High energy 1 2 3 Low energy

21. Electrons in an Atom: Energy Wells Fill the lowest energy orbitals first free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s Energy It is negative for a bound electron Zero Energy

22. Hydrogen free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

23. Helium free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

24. Lithium free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

25. Beryllium free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

26. Boron free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

27. Carbon free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

28. Nitrogen free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

29. Oxygen free electron 1s 2s 2p Level 1 Level 2 Level 3 3 d 3 p 3s

30. What is the maximum number of electrons in the entire set of p orbitals of any given shell? 1. 1 2. 2 3. 3 4. 6 0 250

31. How many orbitals all together are in the third shell by itself? 1. 3 2. 5 3. 9 4. 16 10 0 250

32. How many electrons total are in an atom that has the first and second shells completely filled? 0 250 10 1. 4 2. 6 3. 10 4. 12

33. Absorption line spectra revisited  The outer electron of any atom can jump up to higher orbitals creating a unique absorption spectrum for that element free electron 1s 2s 2p Level 1 Level 2 Level 3 3d 3p 3s

34. Emission line spectra revisited  It can then fall down creating the emission spectrum for that element. free electron 1s 2s 2p Level 1 Level 2 Level 3 3d 3p 3s