Electron Configurations

1
Electron Configurations

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• Mr. Chan
• Northwestern University

2
Day 26

• (0-10) Discuss Tests
• (10-15) Flame Tests Demo
• Blue, Orange/Blue, New Trier
• (15-20) Review Atomic Model
• (20-35) Development of Atomic Theory Bohrs
  Model
• (35-43) Activity/HW Head Start
• Practice drawing Bohr model main group elements
  discuss similarities
• (0-43) Odds/Ends
• Check in Syllabus
• Peer Review Lab

3
Review Atomic Theory thus far

• Dalton (1766-1844)
• Thomson (1856-1940)
• Rutherford (1871-1937)
• Where are those electrons?
• Niels Bohr model (1885-1962)
• Electrons arranged in concentric circular orbits
  (planetary model)
• Levels hold different numbers of electrons
• 2, 8, 8 1st 3 levels
• Staircase, ladder analogies discrete energy
  levels
• Quantum energy required to move an electron
  from present level to next higher one
• Levels can be unequally spaced
• Higher the electron, steps become closer together

4
Bohr Model
5
Day 27

• (0-5) warmup
• (5-20) Atomic Orbitals
• (20-25) CW Orbitals
• (25-35) Electron Configs
• (0-10) CW Practice E-Configs
• (10-30) Constructing P-Table
• (30-35) HW Head Start

6
Energy Levels and Atomic Orbitals

• Compare to stadium seating Levels, aisles,
  rows, seats
• Principal energy levels (n) - section
• Sublevels - aisles
• Atomic orbitals (each can hold 2 electrons)
  row/seat
• S
• P
• D
• F
• 1st energy level
• S orbital
• 2nd energy level
• 2s, 3 2ps
• 3rd energy level
• 3s, 3 3ps, 5 3ds
• 4th energy level
• 4s, 3 4ps, 5 4ds, 7 4fs

7
How do the electrons arrange themselves?

• Electron configurations
• Ways in which electrons are arranged around the
  nuclei of atoms
• 3 Rules of Guidance
• Aufbau principle
• Electrons enter orbitals of lowest energy first
• Show filling order
• Pauli exclusion principle
• Atomic orbital can only hold two electrons
• Electrons must be of opposite spin
• Hunds rule
• Electrons will fill each orbital in a sublevel
  before pairing up to complete orbital
• Examples B, F, any element!
• Practice 5-6
• Note orbital diagrams and shorthand configurations

8
Day 28

• (0-10) Warmup/Review
• Flourine, Phosphorus, Nickel
• (10-25) Review Terms
• Aufbau principle, Pauli exclusion principle,
  Hunds rule, discuss electron configurations
• (25-43) Group Activity
• Making our own P-Table
• (0-10) Discuss HW
• (10-43) More on HW, Plan/ACT Prep

9
Next Quantum Mechanical Model

• Schrodingers model (1887-1961)
• Modern description of the electrons in atoms
  Quantum theory
• Restricts energy of electrons to certain values,
  BUT does not define specific orbits
• Estimates probability of finding electrons in
  certain positions
• Electron cloud model recall Hit the Penny
  activity

10
What do Atomic Orbitals look like?

• http//www.shef.ac.uk/chemistry/orbitron/
• http//web.mit.edu/3.091/www/orbs/

11
HONORS - Exceptions to Electron Configurations

• Chromium
• Special stability with half filled orbitals
• Copper
• Special stability with full orbitals
• Electron configurations of ions?

12
Day 29

• (0-5) Discuss HW
• (5-15) Chapter 12 Quiz
• (15-43) Video
• Movie 1 Hydrogen Atom

13
Day 30

• (0-5) Discuss Chapter 12 Quiz
• (5-25) Waves and Light, Intro Atomic Spectra
• (25-30) WintOGreen LIfesavers demo
• (30-43) Waves activity
• (0-43) Flame Tests Lab

14
Properties of Waves

• Properties of Waves
• Crests, Troughs
• Amplitude (A)
• Height of the wave from origin to crest
• Wavelength (lambda)
• Distance between crests, troughs, or point
• Frequency
• Number of wave cycles to pass point per unit of
  time
• Units cycles per second hertz
• Equation
• Frequency speed of light/wavelength
• Note relationships between variables-
  direct/indirect proportions
• Light through a prism produces continuous
  spectrum of colors
• What happens when element is heated?
• Emits light through spectrum produces atomic
  emission spectrum

15
Using Frequency, Wavelength, Speed light equation

• Velocity, frequency, and wavelength
• C f l
• Example frequency of yellow light 5.10 x 1014
  Hz
• Example What is frequency of radiation whose
  wavelength is 5.00 x 10-6 cm?
• Practice 11-12

16
Day 31

• Warmup cvl (0-5)
• Start Lab prelab, cover sheet (5-15)
• Part 2 Lab Atomic Spectra (5-20, 15-30)
• Part 3 Lab Flame Tests (20-40, 30-43,0-15)
• Clean up/Reflect (40-43)
• Atomic Spectra of Elements (0-15, 15-30)
• The Photoelectric Effect (15-20, 30-35)
• Discuss HW (35-43)

17
Atomic Spectrum

• Background information for Schrodingers equation
  and quantum mechanical modelElectromagnetic
  radiation
• EM spectrumRadio waves, microwaves, visible
  light, infrared, UV light, X-rays, gamma rays
• Light as a continuous spectrum
• Light colors are different frequencies and
  wavelengths
• Sunlight through prism light separates into
  spectrum of colors
• ROYGBIV
• Looking at elements that are heated by passing
  electricity through spectrum gives atomic
  emission spectrum of element
• Many expecting continuous spectrum for atoms
• Instead, a line spectrum was observed
• Each element has a unique line spectrum
• Show spectral chart

18
Photoelectric Effect

• Light has wave behavior as well as particle
  behavior
• Energy emitted when electrons return from excited
  states
• Photoelectric effect Einsteins contribution to
  light as particle theory
• Energy absorbed or emitted proportional to the
  frequency of radiation
• E h v (energy of photons)
• h 6.62 x 10-34 J s (Plancks constant)
• Metals eject electrons when light shines on them
• Examples
• What is energy of photon of microwave radiation
  whose frequency is 3.20 x 1011 s-1
• Calculate the energy (in Joules) of a photon
  whose frequency is 5.00 x 1015 s-1
• Practice 13-14

19
Day 32

• 0-15 Discuss HW 8, 10 Jigsaw?
• 15-30 How to study, Organize syllabus, Review WS
• 30-43 Discuss Review WS
• 0-10 Quiz Show Questions
• Energy Levels and Orbitals - Do you have room for
  more?
• Electron Configurations Can I get your digits?
• Name that Element -
• Waves and Light Can you see the light?
• Wave Calculations My 2 formulas
• 10-43 Review Quiz Show

20
Day 33

• Test

21
Atomic Spectra

• Ground state configurations
• Absorb and releasing energy for electrons
• de Broglies equation
• All matter exhibits wavelike motions
• Heisenberg uncertainty principle
• Impossible to know exactly both the velocity and
  the position of a particle at the same time

22
Lab Flame Tests

• Objectives
• Observe flame test for different metallic ions
• Identify an unknown metal using flame test
• Technique Notes
• Wooden splints instead of wire loops (No HCl)
• Unknown contains mixture of salts
• Hypothesis
• What color of light is associated with the most
  energy?
• What is happening to the electrons of the metal
  when the metal is heated to high temperatures?