Modern Atomic Theory

1
Chapter 10

• Modern Atomic Theory

2
10.2 Electromagnetic Radiation

• EMR energy that travels through space
• as waves
• Is sound an example of EMR?
• Wave 3 properties
• A. Wavelength (lambda) ?
• B. Frequency (nu) ?
• C. Speed

3
Waves

• Wavelength measure peak to peak
• Frequency number of peaks that pass a point in
  a given period of time
• Speed how fast a wave moves through water
• See Figure 10.4 on page 282

4
Light

• Page 282 light as a wave and light as photons
• Photons- packets of energy
• Figure 10.6 Long waves lower energy
• Shorter waves higher energy

5
Emission of Energy by Atoms

• Excited atom has gained energy and is unstable
• Atoms seek stability lowest energy state
  possible
• Atoms will emit energy to become more stable and
  return to ground state
• Pages 284-285

6
An Apparent Contradiction

• Wave-Particle Duality of Nature
• Electrons can behave as either waves or particles

7
Newtonian Quantum Mechanics

• Newtonian Mechanics (classical mechanics)
  describes visible objects at ordinary velocities
• Quantum Mechanics describes extremely small
  particles traveling near the velocity of light

8
Heisenburg Uncertainty Principle

• Werner Heisenberg German physicist
• It is impossible to know the exact position and
  velocity of a moving object at the same time.

9
Schrodingers Work

• Erwin Schrodinger Austrian Physicist
• Heisenberg treated the electron as a particle
• Schrodinger treated the electron as a wave

10
Max Born

• Born used Schrodingers Equation to calculate the
  probability of finding an electron
• Led to the concept of the electron cloud
• Electron cloud has a vague and uncertain volume

11
4 Quantum Numbers

• Schrodingers equation uses 4 quantum numbers to
  describe an electron
• Principal Quantum Number (N)
• Tells distance from the nucleus
• Tells the amount of energy
• Maximum No. of electrons in an energy level is 2
  N squared

12
Electron Arrangement Chart
13
Electron Arrangement Chart
14
Electron Arrangement Chart
15
2nd Quantum No.

• L, refers to the sublevel within an energy level
• The principal quantum no. tells you the number of
  sublevels per level, they have the same value

16
Electron Arrangement Chart
17
Electron Arrangement Chart
18
Orbitals

• An orbital is the space shared by a pair of
  electrons
• An orbital can hold a maximum of 2 electrons. It
  may contain less.
• Sublevels are made up of orbitals

19
Electron Arrangement Chart
20
Electron Arrangement Chart
21
Electron Arrangement Chart
22
Electron Arrangement Chart
23
Electron Arrangement Chart
24
Electron Arrangement Chart
25
3rd Quantum No.

• Third Quantum No., m, defines each orbital
  precisely by indicating its orientation in space.

26
Degenerate

• Orbitals in the same energy sublevel have the
  same energy content.
• The 3 3p orbitals have the same eneregy and are
  said to be degerate

27
Electron Arrangement Chart
28
Electron Arrangement Chart
29
Electron Arrangement Chart
30
Electron Arrangement Chart
31
Electron Arrangement Chart
32
Electron Arrangement Chart
33
Electron Arrangement Chart
34
Electron Arrangement Chart
35
Electron Arrangement Chart
36
Electron Arrangement Chart
37
Electron Arrangement Chart
38
Electron Arrangement Chart
39
Electron Arrangement Chart
40
Electron Arrangement Chart
41
Electron Arrangement Chart
42
Electron Arrangement Chart
43
Electron Arrangement Chart
44
Pauli Exclusion Principle

• No 2 electrons can have the same set of 4 quantum
  numbers.

45
The 4 Quantum Numbers

• 1.) The principal quantum no. (N) is the energy
  level number. It gives information about the
  side and energy of the level.

46
The 4 Quantum Numbers

• 2.) The second quantum number, l, is the energy
  sublevel number. It gives information about the
  shape of the electron cloud.

47
The 4 Quantum Numbers

• 3.) The third quantum number, m, is the orbital
  quantum number. It gives information about the
  orientation in space of the orbital.

48
The 4 Quantum Numbers

• 4.) The fourth quantum number, s, is the spin
  quantum number. Electrons sharing an orbital
  must have opposite spins. One spins clockwise
  and the other counter-clockwise.

49
Distributing Electrons

• Electron Configuration Notation
• Orbital Notation
• Electron Dot Notation