1. Parts of Unit 4 part b Electrons and Periodic Behavior
Cartoon courtesy of NearingZero.net

2. Wave-Particle Duality
JJ Thomson won the Nobel prize for describing the electron as a particle.
His son, George Thomson won the Nobel prize for describing the wave-like nature of the electron.
The electron is a particle!
The electron is an energy wave!

3. The Wave-like Electron
The electron propagates through space as an energy wave. To understand the atom, one must understand the behavior of electromagnetic waves.
Louis deBroglie

4. Electromagnetic radiation propagates through space as a wave moving at the speed of light.
C = speed of light, a constant (3.00 x 108 m/s)
 = frequency, in units of hertz (hz, sec-1)
 = wavelength, in meters

5. Types of electromagnetic radiation:

6. Long Wavelength = Low Frequency Low ENERGY Short Wavelength =
Wavelength Table
Short
Wavelength =
High Frequency
High ENERGY

7. Spectroscopic analysis of the hydrogen spectrum…
…produces a “bright line” spectrum

8. Spectroscopic analysis of the visible spectrum…
…produces all of the colors in a continuous spectrum

10. Photoelectric Effect animation10

11. Excited atom Bohr's Atom: Quantum Behavior in Hydrogen
Close  
Bohr's Atom: Quantum Behavior in Hydrogen
Concept Simulation - reenacts electron's 'jump' and 'fall' to precise energy levels in a hydrogen atom.
© , Visionlearning, Inc. 11

12. The energy (E ) of electromagnetic radiation is directly proportional to the frequency () of the radiation.
E = h
E = Energy, in units of Joules (kg·m2/s2)
h = Planck’s constant (6.626 x J·s)
 = frequency, in units of hertz (hz, sec-1)

13. Electron transitions involve jumps of definite amounts of energy.
This produces bands
of light with definite
wavelengths.

14. Quantum Numbers
Each electron in an atom has a unique set of 4 quantum numbers which describe it.
Principal quantum number
(n) = main energy level and number of sublevels (s,p,d,f,)
n2 = number of orbits in the sublevels
2n2 = number of total number of electrons
Angular momentum quantum number
Magnetic quantum number
Spin quantum number +1/2 , -1/2

15. Heisenberg Uncertainty Principle
“One cannot simultaneously determine both the position and momentum of an electron.”
You can find out where the electron is, but not where it is going.
OR…
You can find out where the electron is going, but not where it is!
Werner
Heisenberg

16. Pauli Exclusion Principle
No two electrons in an atom can have the same four quantum numbers.
Wolfgang
Pauli

17. Principal Quantum Number
Generally symbolized by n, it denotes the shell (energy level) in which the electron is located.
Number of electrons that can fit in a shell:
2n2

18. Sizes of s orbitals Orbitals of the same shape (s, for instance) grow
larger as n increases…
Nodes are regions of low probability within an
orbital.

19. The s orbital has a spherical shape centered around
the origin of the three axes in space.
s orbital shape

20. P orbital shape There are three dumbbell-shaped p orbitals in
each energy level above n = 1, each assigned to
its own axis (x, y and z) in space.

21. Things get a bit more complicated with the five d orbitals that are found in the d sublevels beginning with n = 3. To remember the shapes, think of “double dumbells”
d orbital shapes
…and a “dumbell
with a donut”!

22. Shape of f orbitals

23. Angular Momentum Quantum Number
The angular momentum quantum number, generally symbolized by l, denotes the orbital (subshell) in which the electron is located.

24. Magnetic Quantum Number
The magnetic quantum number, generally symbolized by m, denotes the orientation of the electron’s orbital with respect to the three axes in space.

25. Assigning the Numbers
The three quantum numbers (n, l, and m) are integers.
The principal quantum number (n) cannot be zero.
n must be 1, 2, 3, etc.
The angular momentum quantum number (l) can be any integer between 0 and n - 1.
For n = 3, l can be either 0, 1, or 2.
The magnetic quantum number (m) can be any integer between -l and +l.
For l = 2, m can be either -2, -1, 0, +1, or +2.

27. Maximum number of electrons
Table 3-6a - Orbital and Electron Capacity for the Four Named Sublevels
Sublevel
# of orbitals
Maximum number of electrons s 1 2 p 3 6 d 5 10 f 7 14

28. Principle energy level (n) Type of sublevel :   
Table 3-6b Orbitals and Electron Capacity of the First Four Principle Energy Levels
Principle energy level (n)
Type of sublevel
Number of orbitals per type
Number of orbitals per level(n2)
Maximum number of electrons (2n2) 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7

29. Orbital Energies  29

32. Remember to start at the beginning of each arrow, and then follow it all of the way to the end, filling in the sublevels that it passes through.  In other words, the order for filling in the sublevels becomes
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p
Each time an “s” and a “p” fill (octet = 8) the next energy level starts

34. Principle, angular momentum, and magnetic quantum numbers: n, l, and ml

35. Spin Quantum Number
Spin quantum number denotes the behavior (direction of spin) of an electron within a magnetic field.
Possibilities for electron spin:

36. Relative Energies for Shells and Orbitals36

37. An orbital is a region within an atom where there is a probability of finding an electron. This is a probability diagram for the s orbital in the first energy level…
Orbital shapes are defined as the surface that
contains 90% of the total electron probability.

38. Orbital filling table

40. Electron configuration of the elements of the first three series