1. Warm-up: Identify 3 facts about electrons Where are the electrons?
Electrons & Electromagnetic Radiation

2. Arrangement in the Atom
Electrons
Arrangement in the Atom

4. Where are the electrons?
Electrons are traveling at 6 x 10⁶m/sec around the nucleus
Perspective of the speed:
How long would it take a space vehicle to travel to the moon at the electron’s speed?

5. Distance from
Earth to Moon:
383,401 km
Fastest travel to the moon
8 hours, 35 minutes
Pluto mission fly-by

6. Electrons: Earth to moon distance: 383,401 km Convert to meters
Calculate the time to travel to the moon at the speed of an electron (6 x 10⁶ m/sec):
Distance = Time x Speed

7. Electrons & Electromagnetic Radiation
By studying the light emitted when heating up a chemical sample, scientists better understood the electron:
Its position in the atom;
Its energy; &
Its role (bonding = forming compounds)
Scientists used the electromagnetic radiation to study electrons

8. Electromagnetic Radiation
Form of energy that has a wave-like properties
Characterized by
Wavelength
Frequency
Energy

10. Electromagnetic spectrum
See video clips: 1. NASA – saved 2.
Visible light
Higher energy than visible light
Lower energy than visible light

12. 12 12

13. Everyday examples of the Electromagnetic Spectrum

14. Electrons will give off electromagnetic radiation
When “energized” by heat, electricity, light or chemical
reactions.
How and why does this happen?

15. Energy exists in photons
A photon has a specific amount (or packet) of energy
Also use the word “quantum of energy”
Photons with different energy will have specific wavelengths related to the energy

17. Bohr’s discovery and model: saved video from Discovery Education Starts with historical perspective

18. Bohr’s Model of the Atom
Electrons orbit the nucleus at:
At the lowest energy level possible
Called the ground state
Electrons can be excited by:
Electricity, light, chemical reactions
When excited, an electron will absorb only a certain amount of energy,
A “packet” of energy called a photon or quantum

19. Bohr’s model When excited, the electron
Will jump to a higher energy level
Called the excited state
The electron does not stay in the excited state but falls back toward the nucleus and releases energy

20. Bohr’s model

21. 21

22. Bohr provided critical information
Ground vs. excited state
Number of electrons that exist at specific energy levels
Bohr’s model works for hydrogen but not for the complex atoms

23. Emission Spectrum Lab
Purpose: To relate the unique emission spectra lines of an element to the energy levels of the atom.
Essential Question: What are the emission spectra for specific elements?

24. This is?

25. How do neon lights produce the glowing colors?
FACTS:
Neon is a colorless, inert (non-reactive, non-flammable) gas
Neon lights are tubes filled with neon gas.

26. Neon atoms Normal conditions Electricity passing through the tube
Electrons are at the ground state
No light (energy) is emitted
Electricity passing through the tube
Atoms absorb energy
Electrons become excited and unstable
Electrons are pulled back toward the nucleus
Electromagnetic radiation is emitted

27. Elements and their electromagnetic radiation
Emissions spectrum
Unique for each element
Electrons are excited by electricity
When they are pulled back by the ____________, they give off __________

28. Emission Spectrum White light Hydrogen: Nitrogen: Mercury: Neon:
Write the order of the colors
Hydrogen:
Nitrogen:
Mercury:
Neon:
Other:

30. Emission Line Spectra

31. Emissions Spectra - Simulation
Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.

32. Emission Spectra Unique for each element
Used to identify elements as part of unknown compounds

33. Hubble Space Telescope

36. Bohr Model Animations for Elements 1-11

37. Electrons in models of atoms
Exploratory Lab
How did scientists figure out the structure of atoms without looking at them? Try out different models by shooting light at the atom. Check how the prediction of the model matches the experimental results.

38. Quantum Model Video – www.teachersdomain.org
(thinking behind current atomic model)
The space in between

39. Video electron arrangement
Video – (low volume)

40. Probable location of the electron
The electron arrangement represents where an electron can be found 90% of the time.

42. Methods for Writing Electron Arrangements
Orbital notation
Electron configuration
Noble gas notation
How are you going to remember the names
for each method of writing the electron arrangement?

43. Where are the electrons?

44. Electron placement analogy Aspen Hotel

45. Hotel Analogy – cont

46. Hotel Analogy – cont

47. Rules for Electron Arrangement
Aufbau: *
Pauli’s exclusion principle:
Hund’s rule:
* Check the diagram for the order of increasing energy level

48. Electron Arrangement Diagram
n= principal energy level
Sublevels – s, p, d, f
Orbitals
Each orbital holds 2 electrons with opposite spins, shown by arrows:

49. Energy Diagram n = principal energy level Sublevels: Orbitals
Electrons & spin
Increasing Energy
Nucleus

54. Energy Diagram n = principal energy level Sublevels: Orbitals
Electrons & spin
Increasing Energy
Examples: Sulfur & Iron
Nucleus

55. Energy Diagram Students: Phosphorus Calcium Krypton
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Increasing Energy
Students:
Phosphorus
Calcium
Krypton
Nucleus

56. Energy Diagram n = principal energy level Sublevels: Orbitals
Electrons & spin
Increasing Energy
Nucleus

57. Energy Diagram n = principal energy level Sublevels: Orbitals
Electrons & spin
Increasing Energy
Nucleus

58. Orbital Notation
The orbital is indicated by a line____ wioth the name written below.
Arrows represent the electrons.
Examples
Ne: ___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Note: You must write both the lines and the orbital designations under the lines

59. Electron Configuration
Element
Atomic #
Orbital diagram
Electron Configuration H He Li Be B C N O F Ne Na

60. Practice Orbital Notation ___ Element Atomic # Z 1s H He ___ ___ Li
___ ___
1s s
1s 2s
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
Element Atomic # Z H He Li Be B

61. Practice C N O F Ne
___ ___ ___ ___ ___
1s s 2p 2p 2p
1s 2s 2p 2p 2p

62. Electron Configuration
Principal energy level + sublevel
Use superscripts to show number of electrons in each sublevel
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

63. Electron Configuration: Sublevel diagram
Determining order: Aufbau rules
n=1
n=2
n=3
n=4
n=5
see figure 5-19 on p.138
Know how to
make this chart!

64. Electron Configuration
Element
Atomic #
Orbital diagram
Electron Configuration H He Li Be B C N O F Ne Na

65. Check your electron configuration answers using the Periodic Table
S, P, D, F
Blocks
Periods 18

66. Valence Electrons
Electrons in the outermost (highest) principal energy level
Important
Participate in bonds to make compounds
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
1s² 2s² 2p⁶ 3s² 3p⁴
1s² 2s² 2p⁶ 3s¹
1s² 2s²
1s¹

67. Electron Configuration
Write
Potassium
Aluminum
Chlorine
Circle the valence electrons.

68. K Al Cl Electron Dot Notation Represents valence electrons
Maximum number = 8
Octet rule: atoms will lose, gain or share electrons to have 8 valence electrons & become stable

69. Introducing Noble Gas Notation
Analyze the following examples and propose the rules for writing Noble Gas Notation.
chlorine [Ne] 3s²3p⁵
iron [Ar] 4s²3d⁶
zinc [Ar] 4s²3d¹⁰
barium [Xe] 6s²

70. Noble Gas Notation Short cut method for electron arrangement
Use the noble gas in the period above the element
Example:
Na 1s² 2s² 2p⁶ 3s¹
Use Neon
Represent neon’s configuration 1s² 2s² 2p⁶
as [Ne]
- Use in Na: [Ne] 3s¹

72. Noble Gas Notation 1s² 2s² 2p⁶ 3s² 3p⁴ Element 1s² 2s² 2p⁶ 3s² 3p⁶

73. Noble Gas Notation Element 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁵

74. Noble Gas Notation 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º 4p⁶ 5s²4d¹⁰ 5p⁵

75. Periodic Table: Order based on Electron Configuration
Identify element
Write atomic number (Z)
Symbol
Circle or highlight the valence electrons
Write the electron dot notation

77. Write the Electron Dot in the correct location for the element

80. Electron Configuration
Aufbau is the Rule.
Note: However, sometimes the electron configurations are written in energy level sequence rather than Aufbau sequence.
This is mostly used for the “d” sublevel.
Aufbau sequence
Ti: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
Energy level sequence
Ti: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²