Start Up

1
Start Up

• Do you think scientists can determine the exact
  location of an electron? Why or why not?
• Is light a particle or a wave?

2
Chapter 5

• Electrons in Atoms

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Bookwork

• THE ELECTRON
• Chapter 5- Read pg 117-141
• Problems 1, 2, 5, 7, 12, 14, 17, 18, 20, 21,
  23, 25, 28, 49, 52, 66
• PERIODIC TABLE
• Chapter 6- Read pg 151-169
• Problems 3, 4, 10, 12, 20, 21, 26, 30, 31, 33,
  36, 38, 41, 47, 61

4
Core Content Terms

• Electron
• Quantum Mechanical Model
• Energy Level
• Ground State
• Spectrum
• Quantum
• Photon

• Valence electrons
• Heisenbergs Uncertainty Principal
• Hunds Rule
• Pauli Exclusion Principle
• Aufbau Principle
• Electron Configuration
• Electron Dot Diagram
• Orbital Notation

5

• Recall
• 5 major atomic models!

6
The Bohr Model

• Electrons travel in discrete orbits around the
  atom's nucleus.
• Chemical properties- determined by the of es
  in outer orbits.

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Bohrs Theory Continued

• Electrons drop from a higher-energy orbit to a
  lower one
• Emit a photon (light quantum) of discrete energy
  (became the basis for quantum theory).
• Bohr won a Nobel Prize in 1922 for this work.

8

• Electron absorbs energy as it moves up a level
• Emits energy as it falls down a level
• Energy in the form of light
• Specific amount of energy is called a photon (or
  quantum)

9
Bohrs Model

• Further away from the nucleus means more energy.
• There is no in between energy
• Energy Levels
• Correspond to periods (rows) on PT

Fifth
Fourth
Third
Increasing energy
Second
First
Nucleus
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The Quantum Mechanical Model

• The Bohr model only worked for one-electron
  system (hydrogen atom)
• Not accurate for atoms with multiple es.
• So, Quantum Model was developed to help answer
  these questions.

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Heisenberg Uncertainty Principle

• It is impossible to know exactly the position and
  velocity of a particle.
• The better we know one, the less we know the
  other.

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Uncertainty
Cartoon by John Richardson for Physics World,
March 1998
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The Quantum Mechanical Model

• Has energy levels for electrons.
• Orbitals -not orbits (not circular lines)
• We only know the probability of finding an
  electron a certain distance from the nucleus.

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Electron Probability Activity

• Fill in center square (nucleus)
• Follow instructions on lab sheet
• If you roll a 1, 2,or 3 ? 1st energy level
• Color a square within the 1st orbit (circle)
• If you roll a 4 or 5 ? 2nd energy level
• Color a square within the 2nd orbit
• If you roll a 6 ? 3rd energy level
• Color a square within the 3rd energy level
• Use a different color for each energy level

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Start Up

• What is the formula to determine the maximum
  number of electrons in each energy level? (use
  your activity from yesterday)
• What is the maximum number of electrons in the
  4th energy level?

16
The Dual Nature of Matter

• A. Matter and energy are related Emc2
• B. As matter gets smaller it behaves more like
  energy

• "As far as the laws of mathematics refer to
  reality, they are not certain as far as they are
  certain, they do not refer to reality."--Albert
  Einstein

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Can something be two things at once?

• Examples

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• Elements emit unique frequencies of visible light
  when heated with a flame (different colors)

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Light Waves

• The behavior of an electron can be modeled by the
  behavior of light.
• Can all be described in terms of
• Amplitude
• Frequency
• Wavelength
• Speed

21
Electromagnetic Radiation

• Energy that exhibits wavelike behavior
• Think of light, gamma rays, microwaves

22
The Electromagnetic Spectrum
23
Waves

• The wavelength, the frequency, and the speed of
  light obey the following relationship
• wavelength x frequency speed of light.
• ? x ? c

c3x108 m/s
24
Particle and Wave?

• Max Planck
• Suggested that light consists of photons.
• Light only gained or lost in specific amounts
  (quanta)
• Photon- no mass, quantum of energy

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How does energy relate to waves?

• The energy (E) of each individual photon of a
  light wave, is proportional to the frequency (?)
  of the light
• E h ?
• h (6.626 x 10-34 Js) is Plancks constant
• Energy can only be in whole number multiples of h

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Example

• If a wavelength of light has a frequency of
  1.3x10-11 Hz, how much energy is involved?
• Identify Variables and Solve
• E
• h
• ?

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Start Up

• What energy is involved if an electron releases a
  photon with a wavelength of 590 nm? (Convert to
  meters 1st!)

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Practice Problems!

• Use the two equations
• ? x ? c
• (Wavelength, frequency, speed of light)
• Wavelength (m, nm, cm)
• Frequency (Hz)
• Speed of light (3x108m/s)
• E h ?
• (Energy, Planks constant, frequency)
• Energy-Joules, Calories
• Planks Constant (Js)
• Frequency (Hz or 1/sec)

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Quantum Theory

• Its all in the numbers or letters
• Quantum Numbers give us the electrons specific
  address.
• No two electrons can have the same set of quantum
  numbers!
• Paulis Exclusion Principle

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Atomic Orbitals

• Principal Quantum Number (n)
• Energy level of the electron
• In each energy level, Schrodingers equation
  describes
• Sublevels (s,p,d,f)
• Shapes called atomic orbitals
• Regions where there is a high probability of
  finding an electron.

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S orbitals

• 1 s orbital for each energy level
• Spherical shaped
• Each s orbital can hold 2 electrons
• Called the 1s, 2s, 3s, etc.. Orbitals
• For 1st energy level s,
  2nd energy level s

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P orbitals

• Start in the 2nd energy level (None in 1st)
• 3 different directions (types)
• Each dumbbell shaped
• Each can hold 2 electrons

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D orbitals

• Start in the 3rd energy level
• 5 types (you dont have to know these)
• Each can hold 2 electrons

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F orbitals

• Start in the 4th energy level
• 7 types (dont have to know them!)
• 2 electrons per type

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The rest of the F orbitals
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Quantum NumbersSummary of n, l, m, s

• To Identify the most probable location of an
  electron
• Energy Level (n)
• Use to find max of electrons in a level 2n2
• Sublevel (l)
• There are 4 sublevels s, p, d, and f
• Each sublevel is composed of one or more
  orbitals, which can hold a pair of electrons.

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Flame Test Lab

• Flame as identification of elements?
• Work in Groups of 4 or less
• Hair must be tied back!
• Each person must turn in their own work!
• Data Table
• Calculations Show each step!
• Unknown A
• Unknown B

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Flame Test Lab
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Flame Test Lab Questions

• Choices Na, Sr, Li, K, Cu
• Put the unknowns in order from high to low
  energy.
• Explain why the order makes sense according to
  what you know about wavelength.
• Why do the different elements in the lab emit
  different frequencies of light?
• Is flame color a good method of element
  identification? Why or why not?

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Start Up

• List the four sublevels and give the maximum
  number of electrons that can be found in each.

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Agenda for 3/3/08

• Start Up
• Gradesheets and pass back work
• Electron Configuration Notes
• Practice WS for EC, ON, EDD

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Quantum NumbersSummary of n, l, m, s

• To Identify the most probable location of an
  electron
• Energy Level (n)
• Use to find max of electrons in a level 2n2
• Sublevel (l)
• There are 4 sublevels s, p, d, and f
• Each sublevel is composed of one or more
  orbitals, which can hold a pair of electrons.

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Quantum NumbersSummary of n, l, m, s

• Orientation (m)
• S is small and spherical
• P is dumbbell shaped on the x, y, or z axis
• Spin (s)
• Spin can be positive or negative
• An orbital must have electrons with opposite spins

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Determine an Electrons AddressElectron
Configuration
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3 Major Rules

• Paulis Exclusion Principle
• No two electrons in the same atom can have the
  same set of quantum numbers
• Aufbau Principle
• Electrons fill the lowest energy levels first
• Hunds Rule (The dealer rule)
• Every one gets one before any gets two

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Electron Configuration

• 1s2

of Electrons
Energy Level
Sublevel (Orbital Shape)
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Order of filling
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Practice

• Write the electron configuration of the following
  elements
• Li
• N
• Ca
• Ti

50
Electron notation

• Electron Configuration (EC)
• Lithium
• Orbital Notation (ON)
• Electron Dot Diagram (EDD)

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Start Up

• Write the electron configuration (and ON EDD)
  for Chromium.

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Agenda

• Pass back portfolios, fill out headings
• More Electron Configuration
• Review for Midterm
• Questions before exams?

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There is a Short Cut!! ?

• Noble Gas Shortcut
• Go to last noble gas and write in brackets.
• Example
• From Start Up Chromium
• Go up one row and over to last noble gas Ar
• Ar 4s2 3d4

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Midterm

• About 70 questions (all multiple choice)
• Review Sheet
• If you paid attention during class, this will be
  an easy test, should boost your grade!
• You will have access to
• periodic table, formulas, some English to metric
  conversions

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Review for Exam

• Chapter 1 Intro to Chemistry, Lab Safety
  Equipment
• Basic definition and types of chemistry
• Know what all equipment looks like and what it is
  used for
• Broken glassware, Chemical spill on body
• Treatment for fires, etc.
• Explain what to do in certain situations

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• Chapter 2 Data Analysis (ScientificMeasurement)
  
• Scientific Design p. 13 11, 12
• Independent variable, Dependent variable,
  Constant, Control- Identify what each is in a
  scenario
• Metric conversions (know the conversions chart
  from kilo through milli) p. 50 80
• Scientific notation p. 50 75, 76
• Density (dm/v) p. 50 72-74
• Precision/Accuracy p. 50 81

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• Chapter 3 Matter and Change
• Kinetic and Potential Energy
• Temperature (Look at examples from class)
• Physical and Chemical Changes p. 82
  39, 40
• Heterogeneous and Homogeneous Mixtures p. 82 49,
  50
• Solutions (solute/solvent), Elements, Compounds
  
• ?Understand concepts and identify which component
  is which when given situations

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• Chapter 4 Atoms
• Illustrate the 5 atomic models. Name and describe
  each.
• Protons, Neutrons, Electrons- mass charge and
  location of each
• Nuclear Force
• How to determine atomic , mass , protons,
  neutrons, electrons p. 72
• How to determine ions charge
• Determine the average atomic mass of an element
  p. 113 67
• Ions/Isotopes- What is the difference?
• Write the number of p, n, e for Ca 2,C-14, and
  N3-

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• Chapter 25 Nuclear Chemistry
• Nuclear equations p. 837 69,72, 87
• Fission/Fusion

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• Chapter 5 Electrons in Atoms
  (Do homework problems!)
• Electron Configuration
• Orbital Notation (arrows)
• Electron Dot Diagram (dots)
• Energy/ Frequency/ Wavelength Problems

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Agenda

• No Start Up- Video Clip
• Ion Electron Configuration
• Element List
• CHEMO Cards
• Review Packet

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Orbital filling table
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Electron Configuration of Ions

• All atoms want to be stable
• Most stable elements- called noble gases
• So, atoms want to have EC like Noble gases.
• Want all electron shells full
• Either lose or gain electrons
• Example Li? Li loses 1e
• 1s22s1 ? 1s2 (Like He)
• Example O? O-2 gains 2es
• 1s22s22p4 ? 1s22s22p6 (Like Ne)

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CHEMO Cards

• Design 2 CHEMO Cards with your choice of the 45
  elements
• This assignment is worth 20 points. 10 points
  for each card.
• Each card will receive
• 5 points for neatness
• 5 points for correctness
• 1 person per class will receive a prize for the
  best card!

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Agenda

• Work on Reviews
• Work on cards
• Go over any questionstalk about test.
• Play CHEMO!
• Exemption Pass
• If you want to use your exemption, 2 choices
• Add 10 (15 points) to your midterm
• Replace one classwork grade up to 30 points
• Grade changes?