1. 1 © 2009 Brooks/Cole - Cengage Test II Raw grades: Hi92 Lo9 Average:37.3 Curve 25 pt. Grades (curved) are posted on BlazeVIEW Look at tests/ask questions after class or Wednesday 9 – 1pm (in my office) Analysis/solutions session can be scheduled if there is interest (email bbscott@valdosta.edu)

2. 2 © 2009 Brooks/Cole - Cengage Midterm Grades Based only on Test 1 (75.7%) and OWL (24.2%) The last day to drop without academic penalty: March 3d, by 11:59 pm; limited to five withdrawals per college life

3. 3 © 2009 Brooks/Cole - Cengage Chapter 6 Chem 1211 Class 13 Atomic Structure

4. 4 © 2009 Brooks/Cole - Cengage Atomic Line Spectra and Niels Bohr Bohr’s theory was a great accomplishment. Rec’d Nobel Prize, 1922 Problems with theory — theory only successful for H.theory only successful for H. introduced quantum idea artificially.introduced quantum idea artificially. So, we go on to QUANTUM or WAVE MECHANICSSo, we go on to QUANTUM or WAVE MECHANICS Niels Bohr (1885-1962)

5. 5 © 2009 Brooks/Cole - Cengage Quantum or Wave Mechanics de Broglie (1924) proposed that all moving objects have wave properties. For light: E = mc 2 E = h = hc / E = h = hc / Therefore, mc = h / Therefore, mc = h / and for particles (mass)(velocity) = h / (mass)(velocity) = h / de Broglie (1924) proposed that all moving objects have wave properties. For light: E = mc 2 E = h = hc / E = h = hc / Therefore, mc = h / Therefore, mc = h / and for particles (mass)(velocity) = h / (mass)(velocity) = h / L. de Broglie (1892-1987)

6. 6 © 2009 Brooks/Cole - Cengage Baseball (115 g) at 100 mph = 1.3 x 10 -32 cm = 1.3 x 10 -32 cm e- with velocity = 1.9 x 10 8 cm/sec = 3.88 x 10 -10 m = 0.388 nm = 3.88 x 10 -10 m = 0.388 nm Experimental proof of wave properties of electrons Quantum or Wave Mechanics PLAY MOVIE

7. 7 © 2009 Brooks/Cole - Cengage Uncertainty Principle Problem of defining nature of electrons in atoms solved by W. Heisenberg. Cannot simultaneously define the position and momentum (= mv) of an electron. We define e- energy exactly but accept limitation that we do not know exact position. Problem of defining nature of electrons in atoms solved by W. Heisenberg. Cannot simultaneously define the position and momentum (= mv) of an electron. We define e- energy exactly but accept limitation that we do not know exact position. W. Heisenberg 1901-1976

8. 8 © 2009 Brooks/Cole - Cengage Schrodinger applied idea of e- behaving as a wave to the problem of electrons in atoms. He developed the WAVE EQUATION Solution gives set of math expressions called WAVE FUNCTIONS,  psi) Each describes an allowed energy state of an e- Quantization introduced naturally. E. Schrodinger 1887-1961 Quantum or Wave Mechanics

9. 9 © 2009 Brooks/Cole - Cengage WAVE FUNCTIONS,   is a function of distance and two angles.  is a function of distance and two angles. Each  corresponds to an ORBITAL — the region of space within which an electron is found. Each  corresponds to an ORBITAL — the region of space within which an electron is found.  does NOT describe the exact location of the electron.  does NOT describe the exact location of the electron.  2 is proportional to the probability of finding an e- at a given point.  2 is proportional to the probability of finding an e- at a given point. There is a set of numbers that are parameters of  : they are called quantum numbers

10. 10 © 2009 Brooks/Cole - Cengage QUANTUM NUMBERS The shape, size, and energy of each orbital is a function of 3 quantum numbers: n (principal) → shell l (angular) → subshell m l (magnetic) → designates an orbital within a subshell According to that numbers, electrons in atom grouped in shells and subshells

11. 11 © 2009 Brooks/Cole - Cengage Subshells & Shells Subshells grouped in shells.Subshells grouped in shells. Each shell has a number called the PRINCIPAL QUANTUM NUMBER, nEach shell has a number called the PRINCIPAL QUANTUM NUMBER, n The principal quantum number of the shell is the number of the period or row of the periodic table where that shell begins.The principal quantum number of the shell is the number of the period or row of the periodic table where that shell begins.

12. 12 © 2009 Brooks/Cole - Cengage Subshells & Shells n = 1 n = 2 n = 3 n = 4

13. 13 © 2009 Brooks/Cole - Cengage Types of Orbitals s orbital p orbital d orbital

14. 14 © 2009 Brooks/Cole - Cengage Orbitals No more than 2 e- assigned to an orbitalNo more than 2 e- assigned to an orbital Orbitals grouped in s, p, d (and f) subshellsOrbitals grouped in s, p, d (and f) subshells s orbitals d orbitals p orbitals

15. 15 © 2009 Brooks/Cole - Cengage s orbitals d orbitals p orbitals s orbitals p orbitals d orbitals No.orbs. No. e- 135 2610

16. 16 © 2009 Brooks/Cole - Cengage SymbolValuesDescription n (major)1, 2, 3,..Orbital size and energy where E = -R(1/n 2 ) l (angular)0, 1, 2,.. n-1Orbital shape or type (subshell) m l (magnetic) -l.. 0..+ l Orbital orientation # of orbitals in subshell = 2 l + 1 # of orbitals in subshell = 2 l + 1 QUANTUM NUMBERS

17. 17 © 2009 Brooks/Cole - Cengage Types of Atomic Orbitals See Active Figure 6.14

18. 18 © 2009 Brooks/Cole - Cengage Shells and Subshells When n = 1, then l = 0 and m l = 0 Therefore, in n = 1, there is 1 type of subshell and that subshell has a single orbital (m l has a single value → 1 orbital) This subshell is labeled s (“ess”) Each shell has 1 orbital labeled s, and it is SPHERICAL in shape.

19. 19 © 2009 Brooks/Cole - Cengage s Orbitals— Always Spherical Dot picture of electron cloud in 1s orbital. Surface density 4πr 2  versus distance Surface of 90% probability sphere See Active Figure 6.13

20. 20 © 2009 Brooks/Cole - Cengage 1s Orbital

21. 21 © 2009 Brooks/Cole - Cengage 2s Orbital

22. 22 © 2009 Brooks/Cole - Cengage 3s Orbital

23. 23 © 2009 Brooks/Cole - Cengage p Orbitals When n = 2, then l = 0 and 1 Therefore, in n = 2 shell there are 2 types of orbitals — 2 subshells For l = 0m l = 0 this is a s subshell this is a s subshell For l = 1 m l = -1, 0, +1 this is a p subshell with 3 orbitals this is a p subshell with 3 orbitals When n = 2, then l = 0 and 1 Therefore, in n = 2 shell there are 2 types of orbitals — 2 subshells For l = 0m l = 0 this is a s subshell this is a s subshell For l = 1 m l = -1, 0, +1 this is a p subshell with 3 orbitals this is a p subshell with 3 orbitals See Screen 6.15 When l = 1, there is a PLANAR NODE thru the nucleus.

24. 24 © 2009 Brooks/Cole - Cengage p Orbitals The three p orbitals lie 90 o apart in space

25. 25 © 2009 Brooks/Cole - Cengage 2p x Orbital 3p x Orbital

26. 26 © 2009 Brooks/Cole - Cengage d Orbitals When n = 3, what are the values of s? l = 0, 1, 2 and so there are 3 subshells in the shell. For l = 0, m l = 0 → s subshell with single orbital → s subshell with single orbital For l = 1, m l = -1, 0, +1 → p subshell with 3 orbitals → p subshell with 3 orbitals For l = 2, m l = -2, -1, 0, +1, +2 → d subshell with 5 orbitals → d subshell with 5 orbitals

27. 27 © 2009 Brooks/Cole - Cengage d Orbitals s orbitals have no planar node ( l = 0) and so are spherical. p orbitals have l = 1, and have 1 planar node, and so are “dumbbell” shaped. This means d orbitals (with l = 2) have 2 planar nodes See Figure 6.15

28. 28 © 2009 Brooks/Cole - Cengage 3d xy Orbital

29. 29 © 2009 Brooks/Cole - Cengage 3d xz Orbital

30. 30 © 2009 Brooks/Cole - Cengage 3d yz Orbital

31. 31 © 2009 Brooks/Cole - Cengage 3d x 2 - y 2 Orbital

32. 32 © 2009 Brooks/Cole - Cengage 3d z 2 Orbital

33. 33 © 2009 Brooks/Cole - Cengage f Orbitals When n = 4, l = 0, 1, 2, 3 so there are 4 subshells in the shell. For l = 0, m l = 0 → s subshell with single orbital → s subshell with single orbital For l = 1, m l = -1, 0, +1 → p subshell with 3 orbitals → p subshell with 3 orbitals For l = 2, m l = -2, -1, 0, +1, +2 → d subshell with 5 orbitals → d subshell with 5 orbitals For l = 3, m l = -3, -2, -1, 0, +1, +2, +3 → f subshell with 7 orbitals → f subshell with 7 orbitals

34. 34 © 2009 Brooks/Cole - Cengage f Orbitals One of 7 possible f orbitals. All have 3 planar nodal surfaces. Can you find the 3 surfaces here?

35. 35 © 2009 Brooks/Cole - Cengage Spherical Nodes Orbitals also have spherical nodesOrbitals also have spherical nodes Number of spherical nodes = n - l - 1Number of spherical nodes = n - l - 1 For a 2s orbital: No. of nodes = 2 - 0 - 1 = 1For a 2s orbital: No. of nodes = 2 - 0 - 1 = 1 2 s orbital

36. 36 © 2009 Brooks/Cole - Cengage Arrangement of Electrons in Atoms Electrons in atoms are arranged as SHELLS (n) SUBSHELLS ( l ) ORBITALS (m l )