1. Quantum Theory and the Electron Cloud WHY IS WHAT WE ARE ABOUT TO STUDY IMPORTANT? Explains the position of electrons Position of electrons determines how atoms react

2. - Light has different wavelengths
RELATION TO CHEMISTRY????
- Bohr excited atoms and they gave off light
- Light has different wavelengths
- Different types of atoms gave off different types of light
WHY?
Position of the electrons

4. Bohr Atom:
a.k.a. planetary model
- thought there was a core (nucleus) with rings of circling electrons
- like planets going around the sun

5. in order to prove this Bohr exposed atoms to different types of energy
gave off different kinds of light
- Found electrons existed in specific levels around the nucleus
- atoms absorbed different kinds of energy and became excited
- lots of energy gives off unique energy changes that can be measured

6. Bohr found: Electrons existed in certain positions around the nucleus Electrons could move back and forth between positions HOWEVER 1. Scientists could not accurately describe how the electrons moved around the nucleus 2. Spectral lines weren’t solid – upon closer examination, spectral lines were found to be made up of several small lines

7. Led to:
WAVE PARTICLE DUALITY NATURE
electron exhibits properties of a particle (piece of matter) and properties of a wave (energy - like light)
WHY??? because it is SOOOOOOOO SMALL
When scientists looked at the electron as a particle OR as a wave, they could not get accurate information to describe the electrons behavior
When scientists looked at the electron as a particle AND as a wave, they could get information that correlated with the electrons behavior

8. using a lot a math and analysis we have the
WAVE-MECHANICAL VIEW OF THE HYDROGEN ATOM
- electron moves around the nucleus in a pattern
- pattern is based on where the electron might be at any one time
EX: people in a room
- if you connect all the possible positions the electron might be in you get a three dimensional shape
EX: ceiling fan
- ELECTRON CLOUD - area of highest probability to find an electron outside of the nucleus
IMPORTANCE: Position of the electron determines how the atom reacts

9. NEON vs SODIUM
Ne - AT# 10 - non reactive
Na - AT# 11 - super reactive
WHY? # of p+ = # of e-
NUMBER AND ARRANGEMENT OF ELECTRONS DETERMINES CHEMICAL REACTIVITY

10. BEHAVIOR OF ELECTRONS IS DESCRIBED BY
QUANTUM NUMBERS
- quantum number - represent the different energy states of the electrons
- energy states - different levels the electrons jump between when the electrons are excited and give off energy - differences between energy states correlates to the emission spectrum
Easy for Hydrogen because it only has one electron
For multi-electron systems (other elements) is gets more difficult because the electrons begin to interact with one another

11. HOWEVER: based on mathematical models from the work of de Broglie and Schrodinger, we can predict the arrangement of electrons around an nucleus BASED ON FOUR QUANTUM NUMBERS: n, l, m, s

12. - each spectral line in an emission spectra = an energy level
n = energy level - how far it is away from the nucleus
- each spectral line in an emission spectra = an energy level
- larger the number
- larger the energy level
- farther from the nucleus
- holds more electrons
How many electrons?
# of electrons per level = 2(n)2
EX: 1st level: n = 1
2(1)2 = 2
2nd level: n = 2
2(2)2 = 8

13. when looking at the spectral lines of multi electron elements lines where actually several lines closely spaced together - scientists concluded that these larger levels were actually made up of different SUBLEVELS l = sublevels - number of sublevels equals "n" 1st energy level - one sublevel 2nd energy level - two 3rd energy level - three 4th energy level - four A level can have only four sublevels maximum

14. 4 kinds of sublevels = s, p, d, f
Names of Sublevels 1 1s

15. 4 kinds of sublevels = s, p, d, f
Names of Sublevels 1 1s 2
2s,2p

16. 4 kinds of sublevels = s, p, d, f
Names of Sublevels 1 1s 2
2s,2p 3
3s,3p,3d

17. 4 kinds of sublevels = s, p, d, f
Names of Sublevels 1 1s 2
2s,2p 3
3s,3p,3d 4
4s,4p,4d,4f

18. 4 kinds of sublevels = s, p, d, f
Names of Sublevels 1 1s 2
2s,2p 3
3s,3p,3d 4
4s,4p,4d,4f 5
5s,5p,5d,5f

19. Energy of Sublevels s is lowest  f the highest
- takes more energy to be in the f sublevel
- sometimes the lowest sublevel of a higher level has a lower energy than the highest sublevel of a lower level
WHY? ITS ALL ABOUT THE STABILITY (lower is more stable) - which means, sometimes an electron would rather be farther away from the nucleus and in a simply shaped sublevel than closer to the nucleus and moving in a complicated pattern

20. Each sublevel holds a specific number of electrons
# of Orbitals
# of electrons s 1 2 p 3 6 d 5 10 f 7 14

22. - each of these pairs will occupy a certain region of space = ORBITAL
-ORBITAL: three dimensional space occupied by a pair of electrons
The number of electron pairs in the sublevel determine the shape of the orbitals - more electrons = more complex shape = higher energy

23. shape of all the orbitals of a sublevel is a sphere
-more complex the shape of the orbitals, the higher the energy of the electrons inside
- so a 4s (simple) is lower energy than 3d (very complex)
Therefore, electrons will occupy a higher, simpler orbital before a lower complex orbital
- Aufbau principle: e- occupy the lowest energy orbitals first

24. Atomic Sublevels – s, p,& d

25. p Sublevel

26. Atomic Sublevels - f

28. the direction of these orbitals in space is defined by the third quantum number
m = direction of orbital in space
how many axes are there in three dimensions?
x, y and z

29. Last Quantum Number s which stands for the spin of the electron
what direction does it move around the nucleus in the orbital?
Values of +1/2 and -1/2
Spin in opposite directions - clockwise and counterclockwise

30. NO TWO ELECTRONS CAN HAVE THE SAME QUANTUM NUMBER
Each electron has its own location
Location of the electron determines its stability
The stability of the electrons determines how the atom will react

31. Electron Configurations
Use the first two quantum numbers (n and l) to show the predicted locations of electrons
electrons fill from lowest energy to the highest energy

32. ORDER OF FILL
For Rote Memory:
1s, 2s 2p, 3s 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s

33. 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d
7s 7p 8s

34. 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d
7s 7p 8s

35. Examples
Hydrogen:

36. Examples
Hydrogen: 1s1

37. Examples
Hydrogen: 1s1 Helium:

38. Examples
Hydrogen: 1s1 Helium: 1s2

39. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium:

40. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium: 1s2 2s1

41. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium: 1s2 2s1 Neon:

42. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium: 1s2 2s1 Neon: 1s2 2s2 2p6

43. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium: 1s2 2s1 Neon: 1s2 2s2 2p6 Sodium:

44. Examples
Hydrogen: 1s1 Helium: 1s2 Lithium: 1s2 2s1 Neon: 1s2 2s2 2p6 Sodium: 1s2 2s2 2p6 3s1

45. 1s ___2s___ 2p___ ___ ___ Electron Sub-level Energy Level Orbital
Filling levels - fill across the orbital first then go back and complete the orbital
EXAMPLE: with the p orbitals - 6 electrons - 6 slots
if there are four electrons - fill three across and then start again so only have one pair
Carbon (At # = 6 = 6 electrons)
1s ___2s___ 2p___ ___ ___
Electron
Sub-level
Energy Level
Orbital

46. Understanding Bonding
WHY? WHY? WHY? WHY? WHY? WHY?
Stability
Importance?
Understanding Bonding
Position of the Electrons, especially the outer electrons (valence electrons) cause bonding = CHEMISTRY

47. LEWIS ELECTRON DOT DIAGRAM
- representation of the electrons in the outer energy level of an atom
- these are the electrons involved in chemical reactions = VALENCE ELECTRONS

48. RULES: 1. Write chemical symbol 2. Write out electron configuration 3
RULES: 1. Write chemical symbol 2. Write out electron configuration 3. Isolate the electrons in the configuration with the largest principle number this is the “n” value - add up number of electrons 4. Place dots around the symbol representing the outer electrons

49. EXAMPLES