Unit 4 Classification of Matter

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					 Unit 2 Atomic/Nuclear
Theory/Periodic Patterns
Unit Sequence
Day       Objectives              Assessments                 Activities & Assignments
1         Hook Interest           Data & Observations,        Alchemist’s Dream Lab,
                                  Gold penny taped in         Write 1 page story of
                                  notebook, 1 page story      fictional discovery &
2         Overview of Atomic      Fireworks Poster Project    History, Chemistry,
          Theory                  Rubric                      Spectra of Fireworks

2         Review basic Atomic     Previous knowledge in       Use atomic mass &
          Structure               notes, Completed            number to draw Bohr
                                  assignment, Cooperative     Models of elements 1-18
                                  Quiz                        odd
3,4,5,6   History of Atomic       Lecture discussions, pair   Lectures, Cathode Ray
          Theory – Dalton,        questions, Dalton Quiz –    Demos, Video Clips,
          Thomson, Rutherford,    Informal, Thomson Quiz,     Flame Tests Lab,
          (Emission Spectra &     Rutherford quiz,            Emission Spectra
          Photoelectric effect)   Comparative Quiz
Unit Sequence
Day   Objectives          Assessments                   Activities & Assignments

7     Isotopes, Avg                                     Book questions, Worksheet
      Atomic Mass, Ions                                 – Problem Solving to be
                                                        developed / Quiz
8-    Radioactivity-      Lab check points, Graphical   Radioactivity Shielding Lab
10    Designing           sharing on doc viewerk,       – Practice Day 1, Collect
      Experiments         data & observations in NB     Good Data Day 2, HW:
                                                        Graph, Share Data Day 3
      ½ Lives             Graphical Results             ½ Lives Blocks
                          ½ Life Quiz                   ½ Life Problems

11    Types of            Informal Quiz                 Notes & Geiger Counter
      Radioactivity                                     Demos
                                                        Book Questions about
                                                        basics & applications
12    Nuclear Equations   Discuss, Review & Quiz        Styrofoam balls demo, Write
                                                        equations for Uranium
                                                        decay series
Unit Sequence
Day   Objectives             Assessments                 Activities & Assignments
13    Understand             Quiz Partner                Book questions, Demo
      Quantum                                            Standing Waves, Video –
      Mechanics                                          Orbitals, Slides, Orbitals.
14    Electron               Discuss as show config vs   Write configurations 1-35
      Configurations         diagram from H  Na,        odd

15    Periodic Patterns of   Quiz – configs, Noble Gas   Discovery discussion &
      Electron               configurations & drawing    decorate patterns of
      Configurations -                                   periodic table, write Noble
                                                         Gas configurations of 1-35
16    History of Periodic    Progress on mystery,        Cochran – Periodic Table
      Table                  discussion feedback, quiz   Mystery, Book questions,
                             partner                     Notes on History
17    Patterns of            Comparing Periodic Groups   Laserdisc demos of
      Periodicity                                        radioactivity, decorate
      -Reactivity,                                       bonds & ions on blank, use
      bonding, ions,                                     data to make graphs &
      atomic radius,                                     interpret patterns
      ionization energy,                                 Element Samp;e
      electronegativity                                  Observations
Unit Sequence
Day   Objectives             Assessments                      Activities & Assignments
13    Understand             Rank atoms vertically &          Find patterns in pictures of
      Patterns of Atomic     horizontally – small to large.   radii. Examine Explanation
      Radius & their Basis   Explain trend of each.
14    Understand how                                          Periodic Card Set
      Periodic Table is                                       Old Periodic Table Fill in
      organized                                               Blank


Vocab 2A
• Atom
• Law of Definite            •   Electromagnetic radiation
    Proportions              •   frequency
•   Law of Conservation of   •   Wavelength
•   Cathode ray              •   Quantum
•   Cathode ray tube         •   Photoelectric effect
•   Electron                 •   Photon
•   Nucleus                  •   Line spectrum
•   Proton                   •   Ground state
•   Neutron                  •   Excited state
•   Atomic mass unit         •   Quantum mechanical
•   Atomic number            •   Orbital
•   Atomic mass              •   Sublevel
•   Ion                      •   Electron configuration
•   Isotope
Vocabulary 2B
Isotope              Radioactive decay
nuclear reactor      critical mass
Radioisotope         Alpha particle
nuclear weapon       nuclear bombardment
Radioactivity        Beta particle
half life            strong nuclear force
Radiation            Gamma ray
nuclear equation      plasma
Fission              Nuclear chain reaction
positron             dosimeter
radiocarbon dating
              Atom Builder Activity

   • http://www.pbs.org/wgbh/aso/tryit/atom/
   • For each addition to the atom (Up to
     Stable Carbon) record the following:

Element   Protons   Neutrons   Electrons   Radioacti Ionized?   Stable?
Bohr Models of Atoms – Parts (1 of 3)

Part        Charge   Mass     Location

Proton      +1       1 amu    Nucleus

Electron    -1       1/1837   Orbiting
                     amu      nucleus
Neutron     0        1 amu    Nucleus
Determining the Part (2 of 3)
Part        How to Determine
Protons     = atomic number (smaller whole
            #) from periodic table
Electrons   = atomic number (smaller whole
            #) from periodic table (assumes
            0 charge, or neutral)
Neutrons    = atomic mass (larger # w/
            decimal, round) – atomic #
Drawing Bohr Models (3 of 3)
Determine number of protons, electrons &
  neutrons in atom.
Draw protons (+) & neutrons (0) in nucleus.
Draw electrons in circles around nucleus:
  - 2 maximum on 1st level.
  - 8 maximum on 2nd level.
  - 18 maximum on 3rd level.
Asmt: Draw elements 1-18 odd (even XC)
  Alchemist’s Dream Review (1 of 2)
Q: How do you tell if it is really gold?
• Archimedes Principle: Determine the volume by
  displacement and then confirm the density.
Q: What did the salty vinegar do?
• Dark pennies have black CuO oxidation.
• Acid in vinegar & salt reduce the Cu+2 back to Cu0 to
  reshine the penny.
Q: How did the pennies turn silver?
• Zinc plates on the outside of the copper.
Q: How did they turn to gold in the flame?
• Heating melts the zinc into the copper to form brass!
  Alchemist’s Dream Review (2 of 2)
Q: Was the removal of black CuO a chemical or physical
A: It chemically changed from black copper salt to
  metallic copper.
Q: Is brass a mixture or a compound?
A: Brass is a mixture and an alloy.
Q: Is the mixture homogeneous or heterogeneous?
A: Ours varied by depth and color. So they were
  heterogeneous. Manufacturers produce homogeneous
Development of Atomic
         History of the atom
• Not the history of atom, but the idea of the
• Original idea Ancient Greece (400 B.C.)
• Democritus and Leucippus- Greek
            John Dalton

• British
• A small town
  school teacher at
  the age of 12.
• Introduced his
  atomic theory in
Previous Findings
1. Law of Conservation of Mass
   Matter is neither created or destroyed in a
   chemical reaction. (Antoine Lavoisier)
2. Law of Definite Proportions
   The percentage by mass of elements in a
   compound is constant for any sample. Ex: H2O
3. Law of Multiple Proportions
   Compounds composed of the same two
   elements differ in one element by simple ratios.
   Ex: CO vs CO2; H2O vs H2O2
       Law of Definite Proportions
• Each compound has a
  specific ratio of elements.
• It is a ratio by mass.
• Water has a mass of 18 grams
  hydrogen 2 atoms x 1.0 grams
  oxygen 1 atom x 16 grams
• The ratio is always 8 grams of oxygen
  for each gram of hydrogen
  (2 g H to 16 g O or 1 g H to 8 g O).
   Law of Multiple Proportions

• Two elements or more elements may form
 more than one compound if they have
 different whole number ratio of each
• Example: water                  H2O
              hydrogen peroxide   H2O2
Daltons Atomic Theory
1. All matter is composed of tiny indivisible
   particles called atoms
2. All atoms of the same element are identical
3. Different elements have different types of
4. Compounds are formed from simple
   combinations of atoms of different elements.
5. In a chemical reaction atoms are simply
*Activity: Ball & Stick Reactions
Picture Dalton’s Atomic Theory
   Updates to Dalton’s Theory
1a. Atoms are divisible into protons,
  neutrons & electrons (& even smaller!).
1b. In nuclear decay they actually fall
2. All atoms of a single element have the
  same number of protons, but not
  neutrons. (isotopes)
4. Compounds may be very complex!
Dalton’s Atomic Theory Quiz
1. What year was his theory published?
2. Which previous finding defined
   compounds as having consistent percent
3. How did Dalton describe chemical
4. How can atoms of the same element be
Cathode Rays
• Tape Lab – Static
  electricity attractions &
  repulsions. Where do the
  charges originate?           (-)   (+)
• An evacuated glass tube
  when placed in an electric
• Crooke’s observed a
  glowing inside.
• Thomson repeated
  Crooke’s experiment and
  did additional
    Thomson’s Experiment #1
• Setup: A cross was
    placed in the path of   Cathode (-)
    the glowing beam.
•   Observation: A           Anode (+)
    shadow appeared on
    the anode (+) side.
•   Interpretation: The
    rays come from the
    cathode (-) side.
    Thomson’s Experiment
         Voltage source
-                         +

         Vacuum tube

          Metal Disks
    Thomson’s Experiment
         Voltage source
-                         +
    Thomson’s Experiment
         Voltage source
-                         +
    Thomson’s Experiment
         Voltage source
-                         +
        Thomson’s Experiment
               Voltage source
    -                                 +

   Passing an electric current makes a beam
    appear to move from the negative to the
                  positive end
        Thomson’s Experiment
               Voltage source
    -                                 +

   Passing an electric current makes a beam
    appear to move from the negative to the
                  positive end
        Thomson’s Experiment
               Voltage source
    -                                 +

   Passing an electric current makes a beam
    appear to move from the negative to the
                  positive end
        Thomson’s Experiment
               Voltage source
    -                                 +

   Passing an electric current makes a beam
    appear to move from the negative to the
                  positive end
Thomson’s Experiment #2
• Setup: The cathode
    ray tube was placed in
    an electric field: (-)
    electrode on top, (+)
    electrode on bottom.
•   Observation: The
    cathode rays were
    attracted towards the
    (+) electrode. (D?)
•   Interpretation:
    Cathode rays must be
    negative (-).
    Thomson’s Experiment #3
• Setup: Cathode rays
    were placed in a
    magnetic field.
•   Observation:
    Cathode rays are bent
    perpendicular to the
    magnetic field.
•   Interpretation:
    Cathode rays are not
    a form of light.
Thomson’s Experiment #4
• Setup: A glass wheel was placed on a
  level track inside the cathode ray tube.
• Observation: Cathode rays can rotate the
  glass wheel.
• Interpretation: Cathode rays are particles
  with mass.
Thomson Experiment #5
• Setup: Thomson made cathode ray tubes
  with a variety of different gases & metal
  electrodes in the tube.
• Observation: Every tube produced the
  same cathode rays.
• Interpretation: Cathode rays are
  fundamental to matter. He called cathode
  rays “electrons!” Discovered in 1897.
Thomson’s Plum Pudding Model

• Thomson concluded
    that all atoms must
    have negative
    charges and positive
    charges to balance
•   Thomson assumed
    that (+) & (-) charges
    would be evenly
    Thomson’s Atomic Model

Thomson believed that the electrons were like plums
embedded in a positively charged “pudding,” thus it
      was called the “plum pudding” model.
Uses of cathode rays
• 1. A cathode ray tube (CRT) is widely used in research laboratories
  to convert any signal (electrical, sound, etc) into visual signals.
  These are called CRT or oscilloscopes.
• 2. CRT is the basic component in all television and computer
  screens. The signals are sent to the vertical and horizontal
  deflecting plates, which produce a pattern on the fluorescent
• High energy cathode rays when stopped suddenly produce X-rays.
  The X-rays have many medical and research applications.
Thomson’s Atomic Theory Quiz
1. How did Thomson know that the rays
   came from the cathode?
2. What did Thomson conclude from
   cathode rays being bent by a magnet?
3. How did Thomson know cathode rays
   were fundamental to matter?
4. In Thomson’s model of the atom where
   is the positive charge?
         Millikan’s Oil Drop Experiment
• the charge of an
  electron with this
  experiment. –1.6 x
  10-19 coulomb
• Thomson and
  Millikan calculated
  the mass of the
  electron to be 9.1
  x 10-28 g. This is
  1/1837 the mass
  of a Hydrogen
• Becquerel - Radioactivity
• Curie – Discovered radioactive elements of
 radium and polonium
1. Alpha particle – is two protons and two
     neutrons bound together and is emitted from
     the nucleus, 2+ charge, 4.0 grams, least
2.   Beta particle – an electron emitted from the
     nucleus 1- charge
3.   Gamma rays are high energy electromagnetic
     waves emitted from the nucleus, most

• Alpha – large
  Relatively slow
• Beta – much smaller
  Relative fast
• Gamma – no mass
  Pure energy
  Travels at the
  Speed of light
Ernest Rutherford
         • New Zealander
         • Discoverer of alpha,
             beta & gamma
         •   Discovered nucleus of
             atom in 1912.
         •   Laserdisc demo – Side
             2, Chapter 20
Rutherford’s Experimental Design

                  • Uranium alpha
                  •   Slits to focus radiation
                  •   Gold foil target.
                  •   Scintillation screen of
                      zinc sulfide to flash
                      when hit.
Rutherford’s Prediction
             Positive alpha particles
               would go straight
               through or have
               minor deflections due
               to the electrons
               embedded in a sea of
               positively charged
Rutherford’s Observations
             Interpreting the Results
• Most positive alpha particles went straight through or were slightly
•   Therefore the atom is mostly empty space.
•   A few positive alpha particles bounced back radically!
•   Thus the atom must have a large concentration of positive charge!
Rutherford’s Atomic Model
    Development of the Bohr Model
• In 1913 Danish
    physicist Neils Bohr
    proposed a new model
    of the atom.
•   Bohr’s Model explained
    the emission and
    absorption patterns of
    light discovered by
    Bunsen in flames &
Emission Lamps
              Emission Spectra
• Each element emits a unique set of bright line wavelengths.
 Emission Spectra of All the Elements

• http://chemistry.beloit.edu/bluelight/movi
• http://jersey.uoregon.edu/vlab/elements/E
• http://www.webelements.com/
  4 Principles of the Bohr Model
1)Electrons assume only certain orbits around the
  nucleus. These orbits are stable and called
  "stationary" orbits.
2)Each orbit has an energy associated with it. The
  lowest energy levels are close to the nucleus.
  The farther from the nucleus corresponds to
  higher energy levels. Electrons tend to occupy
  the lowest energy levels available.
3)Light is emitted when an electron jumps from a
  higher orbit to a lower orbit. Light is absorbed
  when it jumps from a lower to higher orbit.
4)The quantity of energy and wavelength of light
  emitted or absorbed is given by the difference
  between the two orbit energies. (Quantum
• With these conditions
    Bohr was able to
    explain the stability of
    atoms as well as the
    emission spectrum of
•   Line spectra correspond
    to quantum leaps
    between levels of
    specific energies.
•   Violet light corresponds
    to high energy
    quantum leaps while
    red light corresponds to
    low energy. ROYGBIV
Excited State                  Ground State

                Green light

                 Red light

Excited State                 Semi-Excited State
       Excited vs Ground States
• Light is absorbed when electrons jump up to
    higher “excited” energy levels.
•   Light is emitted when electrons jump back down
    to their lowest energy “ground” state energy
•   Animated Absorption & Emission
•   Fluorescent lights are constantly exciting gas
    atoms to emit light by passing a stream of
    electrons through the interior gas.
         The Sun’s Spectra
• Many elements
  can be identified
  by their unique
• Helium was 1st
  discovered in the
  Sun’s (Helios)
Emission vs Absorption
Colors Lab A. Flame Tests
Asthmatics may be excused
Test 10 known compounds & 3 unlabeled to identify.
Make data table:

#     Salt           Salt             Flame Color &
      Formula        Appearance       Effects
Colors Lab B. Spectral Emissions

Lamp # of Colors of   Line Pattern   ID
#    Lines ROYGBIV                   Element
             Comparing Atomic Models
             Dalton   Thomson   Rutherford Bohr

Picture of

Atomic & Nuclear Chemistry
 Geiger Counter Demos
   Sample         Counts per   Reason
  NaCl vs KCl
Smoke Detector
Old Fashioned
Lantern Mantle
Old Glow in the
  Dark Clock
 Uranium Ore
  Radioactivity (PS1 Ch26, )
 Types of     Alpha        Beta           Gamma
  Symbol      a (He)       b (e-)             g

   Mass       4 amu       1/1837           0 amu
  Charge       +2           -1           0 (movie)

Composition 2 protons,   1 electron     High energy
            2 neutrons                    photon
Penetration Blocked by     Sheet      Blocked by 1ft of
               paper       metal      concrete or few
                                       inches of lead
        Alpha Emission

263           4            259
   Sg             He   +      Rf
106           2            104

• The unstable nucleus simultaneously
  ejects two neutrons and two protons,
  which correspond to a helium nucleus.
• The emission of gamma photons is a
  secondary reaction that occurs a few
  thousandths of a second after the
         Beta Emission

14            0           14
     C            e   +        N   +   g
 6           -1            7
Gamma Radiation
Radioactivity Shielding Lab
Essential Question:
  There are a variety of medical diagnostic
  equipment which use radioactive materials
  inside. What is the most efficient way for
  manufacturers to cut down exposure for
  patients & medical staff?

 Geiger Counter, Lead box, Uranium Ore
 Sample, Ruler, Stop Watch,

Shielding Material Options:
  water, paper, plastic, cardboard, glass,
  ceramic tiles, aluminum foil, sheet copper
Radioactivity Shielding Lab

What variables can we change?
Distance vs Radioactivity
             1st Trial   2nd Trial   Average
Shielding Material vs Radioactivity

Select 5    1st Trial   2nd Trial   Average
   Radioactivity Lab Directions (1 of 2)
As a lab group:
Part A: Investigate the effect of distance on
   radioactivity over at least 5 different levels.
1. Write an “if, then” hypothesis.
2. Write a reason for your hypothesis.
Part B: Investigate the effect of a shielding material on
1. Choose your unique material to vary over at least 5
   different levels.
2. Write an “If, then” hypothesis.
3. Write a reason for your hypothesis.
4. Use distances that produce as large of counts as
Safety Guidelines:

1. Always keep sample in lead box.
2. Always face opening towards the wall.
3. Rotate counters to minimize exposure.
Lab Requirements
• Determine the background radiation
• Use as our baselines the highest countable
  radioactivity possible.
• At least 5 different levels for each
Controlled Variables
Distance                 Shielding
• same equipment,        • same shielding
• distance increments,     material,
• time,                  • distance,
• Positions & angles     • material additions,
                         • time
How Organize your Data Table?

Required Elements:
• Level – distance or shielding
• Trial – 1st, 2nd, or 3rd repetition
• Counts – per minute (or variation)
• Observations – things you notice and
  record verbally like sources of error.
Finish Geiger Lab – Due Friday
       Pick Your Roles & Rock & Roll:
                Safety officer
   Set up experiments – Control distance?
                 Count clicks
             Time experiments.
                Record data
             Calculate averages
             Make Excel graph
     Powerpoint lab report – start now.
Recommendations for Minimizing
Radiation Exposure
Based on the findings of the class, what do you
  recommend that manufacturers use to most
  efficiently and effectively protect patients and
  employees from unnecessary exposure to
  radioactive diagnostic equipment? Write your
  recommendation in full sentences. Mention at
  least 2 factors.
XC How could we test to see if radioactivity
  reflects off of the material used. Diagram the
  set up.
Side 10 - Chapter 2 – Ancient Cultures –
  Archaeology – C14 Dating
Side 10 – PET Scan – Positrons – ½ lives
Gamma rays
   Geiger Lab Rubric
Presentation   Points made     Summarizing      Summarizing,      Reading to
Skills         clearly &       information      but lacking       audience,
               concisely       clearly.         clarity.          lacking eye
                                                                  contact or
                                                                  loud voices.
Experimental All external      Internal         Lacking           Clear
Design       influences        variables of     controls on       independent &
             controlled as     experiment       internal          dependent
             well.             controlled       variables.        variable.
Data &         Complete set    Complete set of One complete       Data missing
Observations   of multiple     2 trials for each set of trials.   from report.
               (>2) trials.    experiment.

Conclusions    Accurately       Uses            Compares          Revisits
               interprets       experimental    results.          hypothesis
               results &        evidence
               applies to life.
• Atoms of a single element have the same
    number of protons but may differ in neutrons.
•   Example 1: Carbon-12 vs Carbon-14
•   Example 2: Uranium-238 vs Uranium-235
•   Some isotopes are stable while others are
    unstable and radioactive.
•   The STRONG NUCLEAR FORCE acts between
    protons & neutrons to hold them together.
    However protons will repel each other with their
    mutual positive charge.
Carbon Isotopes
Isotope         Half – life
                              • How long does it take
Carbon –   9    0.1265 s
                                400 g of each isotope
Carbon –   10   19.2 s          to decay to less than
Carbon –   11   20.38 min       1 mg?
Carbon –   12   Stable
Carbon –   13   Stable
Carbon –   14   5715 y
Carbon –   15   2.449 s
Carbon –   16   0.75 s
  Beanium – Average Atomic Mass Activity
7. Find the average mass of each of the 3 beanium
Average mass of ___ beans = subtotal mass/#of
8. % Abundance of each type =
# of beans/total beans (x100 to make a %)
10. Average beanium atomic mass
= (%white x avg mass white)
+ (%black x avg black mass)
+ (%red x avg red mass)
*Convert the %s back into decimals to do #10.
    Uranium Decay Series
• U238 alpha - HL            •   Po218 alpha – HL 3.10m
    4.468e9y                 •   Pb214 beta – HL 26.8m
•   Th234 beta – HL 24.10d   •   Bi214 beta – HL 19.9m
•   Pa234 beta – HL 6.70h    •   Po214 alpha – HL 164.3
•   U234 alpha – HL              ms
    245,500y                 •   Pb210 beta – HL 22.6y
•   Th230 alpha – HL         •   Bi210 beta – HL 138d
    75,380y                  •   Po210 alpha – HL
•   Ra226 alpha – HL1600y        4.199m
•   Rn222 alpha – HL         •   Pb206 Stable!
Nuclear Reactions
• Radioactivity results from changes in
  atomic nuclei.
• Fission – splitting of a large nucleus into
  smaller pieces releases energy.
• Fusion – small nuclei join to make a larger
  nucleus and release energy. (PS1, Ch25)
• Energy is released when a small amount
  of mass converts to energy as E = mc2.
Fusion of Hydrogen Isotopes
                   • At high temperatures
                       and pressures, 2
                       nuclei may collide and
                       form a bigger nucleus.
                   •   This example produces
                       helium and a stray
                   •   Stars are fueled by the
                       energy released by
                       fusion which also
                       builds atoms of
                       increasing sizes in
                       their cores.
Fission of Uranium
                     • A neutron splits the
                     •   The fragments include:
                          – 2 different smaller
                          – 3 more neutrons.
                     •   The 3 neutrons can split
                         more atoms.
                     •   If every fission splits 3
                         more atoms, the
                         reaction will multiply out
                         of control!
Nuclear Equations

• Styrofoam Demos
• Alpha Decay – releases a helium nucleus.
• Beta Decay – a neutron converts to a
  proton and releases an electron.
• Assignment: Uranium Decay Series
Nuclear Warheads
Chernobyl Nuclear Disaster
Nuclear Equations Problems
1.  U–238 does alpha decay in nuclear reactors.
2.  Am-241 does alpha decay in smoke alarms.
3.  Tc-98 does beta decay in medical exams.
4.  C–14 does beta decay in carbon dating.
5.  The Curies used Ra-226 which does alpha
6. Co–60 does beta decay in food irradiation.
7. Th-232 does alpha decay in camp lanterns.
8. P-35 does beta decay in DNA studies
(Place isotopes activity in Outbox)
Nuclear Equations Quiz
1.Write the nuclear
  equation for the alpha
  decay of Iodine 131.
2.Write the nuclear
  equation for the beta
  decay of cobalt 60.
½ Lives Activity
• Obtain a set of “radioactive” blocks. Notice that each one
    has a mark on one side – either a, b or g.
•   Roll the collection of blocks onto your table. Each time you
    roll, remove any blocks that come up a, b or g.
•   Count and record the remaining blocks. Roll the remaining
    blocks repeatedly 20 times and complete the chart below.
•   Enter your group data into the excel file.
•   Make graphs of Time(minutes) Remaining Atoms for both
    individual & class averages. **Use “exponential” rather than
    “linear” trendlines.

    Roll                Remaining             Class Average
    (minutes)           Atoms
½ Lives Activity Questions

1. How do your lab pair results compare
   with the class average results?
2. Use the class average results and
   compute the 1st ½ life, 2nd ½ life,
   average ½ life.
3. What importance do ½ lives have to
   (dating, medical uses, wastes)
½ Lives
• Each radio-isotope decays at a characteristic
•   The decay rate is determined by the time that it
    takes for ½ of the radio-isotope nuclei to break
    down by fission.
•   Each ½ life reduces the remaining number of
    radioactive atoms by ½.
•   The number remaining approaches but never
    reaches zero.
•   Example: Iodine 131 has a ½ life of 8 days.
    How much of 1.00 gram sample would remain
    after 24 days?
Solving ½ Life Problems
Masses:                       Times:
• STARTING                    • Time for 1 half
  MASS            # of half     life (HL)
• Divided in ½    lives       • Total time
  the # of half                 elapsed (T)
  lives.                      • T = HL*(#)
• ending mass                 • HL = T/#
                              • # = T/HL
½ Life Problems
1. If you have $1 million dollars and every 2
   seconds it decreases by 1/2, how long will it
   take until you are penniless?
2. If a sample of a fossil mammoth has 1/8th the
   amount of carbon 14 as it would today, how
   old must the fossil be? (1/2L C14 = 5715
3. If a rock contained 1.2 g of potassium 40
   when it formed, how many grams remain after
   4 billion years. (1/2L K40 = 1.33E9 y)
Asmt: P780 #1&2, P803 #24&25
 More ½ Life Problems
4. If a sample of radioactive isotope has a half-life of 1 year,
    how much of the original sample will be left at the end of
    the second year? The third year? The fourth year?
5. The isotope cesium-137, which has a half-life of 30
    years, is a product of nuclear power plants. How long
    will it take for this isotope to decay to about one-
    sixteenth its original amount?
6. Iodine-131 has a half-life of 8 days. What fraction of the
    original sample would remain at the end of 32 days?
7. The half-life of chromium-51 is 28 days. If the sample
    contained 510 grams, how much chromium would
    remain after 56 days? How much would remain after 1
½ Lives Quiz
1. A sample of a radioactive isotope with an
  original mass of 8.00g is observed for 30 days.
  After that time, 0.25g of the isotope remains.
  What is its half-life?
2. The starting mass of a radioactive isotope is
  20.0g. The half-life period of this isotope is 2
  days. The sample is observed for 14 days.
  What PERCENTAGE of the original amount
  remains after 14 days?
Health Physics Society
• http://hps.org/publicinformation/ate/q754.html

• Q:What are some health effects of the element uranium?

• A:The toxicity of uranium has been under study for over 50 years,
  including life-span studies in small animals. Depleted uranium and
  natural uranium both consist primarily of the uranium isotope 238U.
  They are only very weakly radioactive and are not hazardous
  radioactive toxicants, but uranium is a weak chemical poison that
  can seriously damage the kidneys at high blood concentrations.
  Virtually all of the observed or expected effects are from
  nephrotoxicity associated with deposition in the kidney tubules and
  glomeruli damage at high blood concentrations of uranium. The
  ionizing radiation doses from depleted and natural uranium are very
  small compared to potential toxic effects from uranium ions in the
  body (primarily damage to kidney tubules).
Modern Atomic Theory
 Quantum Mechanical Model
   (Electron Cloud Model)
Electrons & Standing Waves

1. Electrons don’t move in straight lines;
   they move as waves.
2. Electron microscopes allow us to see flies
   eyes since electron wavelengths are
   shorter than visible light waves.
3. Electrons orbiting a positive nucleus
   settle into low energy standing waves
4. Demo – Standing waves
1. Electron wave orbits are
    too complicated to
2. Chemists describe their
    probable location as
3. Orbitals are defined as
    the space they occupy
    90% of the time.
4. Demo: Electrons
    occupy orbitals like fan
Orbital Demos
1. Electrons move so fast they occupy
   space like fan blades!
2. The most stable patterns for electron
   wave motions are standing waves!
3. *Electrons move fastest passing the
   nucleus and spend little time there.
1. Orbital Diagrams
2. Video – CheMedia Side 2, Chapter 23
F orbitals
 • Start at the fourth energy level
 • Have seven different shapes
 • 2 electrons per shape for a total of 14
F orbitals
Electron Orbitals
Type    Shape        Set   1st Occur

S       Spherical    1     Level 1

P       Dumb-bell    3     Level 2

D       Cloverleaf   5     Level 3

F       8 Lobed      7     Level 4
Electron Configurations

• Orbitals can hold 2 electrons each.
• Lowest energy orbitals fill first.
• Electrons repel and occupy separate
  orbitals on the same energy level if
• Orbital Packing Key:
• 1s22s22p63s23p64s23d104p65s24d105p6…….
• Animated Electron Configurations
Orbital filling table
 Electron Configurations vs Pictures
1 H 1s1

 Electron Configurations vs Pictures
1 H 1s1
2 He 1s2

                 -   ++ -
 Electron Configurations vs Pictures
1 H 1s1
2 He 1s2
3 Li 1s22s1
                     -   ++
                          + -

 Electron Configurations vs Pictures
1 H 1s1
2 He 1s2
3 Li 1s22s1                     -

                     -   ++
4 Be   1s22s2            ++ -

 Electron Configurations vs Pictures
1 H 1s1
2 He 1s2                -

3 Li 1s22s1                    -

                     - ++ +
4 Be   1s22s2           ++ -

5 B 1s22s22p1    -
 Electron Configurations vs Pictures
1 H 1s1
2 He 1s2                -

3 Li 1s22s1                   -

                     - ++
4 Be 1s22s2             + -       -

5 B 1s22s22p1    -

6 C 1s22s22p2
 Electron Configurations vs Pictures
1 H 1s1                                  7N 1s22s22p3
2 He 1s2                   -

3 Li 1s22s1                      -

                        - ++
4 Be 1s22s2               ++ -       -

5 B 1s22s22p1   -

6 C 1s22s22p2
 Electron Configurations vs Pictures
1 H 1s1                                    7N 1s22s22p3
2 He 1s2                    -              8O 1s22s22p4
3 Li 1s22s1                        -

                        - + ++
4 Be 1s22s2     -          + + -       -

5 B 1s22s22p1   -

6 C 1s22s22p2
 Electron Configurations vs Pictures
1 H 1s1                                     7N 1s22s22p3
2 He 1s2                    -               8O 1s22s22p4
3 Li 1s22s1                         -
                                            9F 1s22s22p5
                        - + ++
4 Be 1s22s2                + + -        -

5 B 1s22s22p1   -

6 C 1s22s22p2
 Electron Configurations vs Pictures
1 H 1s1                                         7N 1s22s22p3
2 He 1s2                    -                   8O 1s22s22p4
3 Li   1s22s1                       -
                                                9F 1s22s22p5
                        - + ++
4 Be 1s22s2                +++ -            -
                                                10Ne 1s22s22p6
5 B 1s22s22p1   -

6 C 1s22s22p2
 Electron Configurations vs Pictures
1 H 1s1                                            7N 1s22s22p3
2 He 1s2           -           -                   8O 1s22s22p4
3 Li   1s22s1                          -
                                                   9F 1s22s22p5
                           - + ++
4 Be 1s22s2                   +++ -            -
                                                   10Ne 1s22s22p6
5 B 1s22s22p1      -

                                   -               11Na
6C     1s22s22p2
Electron Configurations vs Pictures

             -           -
                     - + ++
                         +++             -
                 -        + -

Electron Configurations vs Pictures

             -           -
                     - + ++
                         +++             -
                 -        + -

Electron Configurations vs Pictures

             -           -
                     - + ++
                         +++             -
                 -        + -


1. Write the electron configuration & draw
   an atom of fluorine.

Asmt: Write electron configurations of
   elements 1,5,9,13,17,21,25,29.
Photoelectric Effect & Solar Energy

• http://www.walter-
• http://phet.colorado.edu/new/simulations/
• http://www1.eere.energy.gov/solar/photo
• http://www.electronsolarenergy.com/reso
Tuesday 11/27/07
1.    See Neil about Periodic Table Activities
2.    Determine Periodic Table book assignment
Periods 1 & 3
DMA: What element corresponds to the configuration [Kr]5s24d105p5?
1. Take & correct quiz
2. Periodic Table Activity
Asmt: Page 163 #1-4, page 173 #1,3, page 185 #2
Plan: Meet with POD
Periods 4-6
Library Utopia Project
1. Grade Poster Projects
2. Contact National Boards about appeal of Active Inquiry
3. Go to Wells Fargo
     1.   Deposit checks, get new registers!
     2.   Provide mortgage documents
Orbital Animations

• Chemedia Laserdisc Demo – Side 2,
  Chapter 23
• http://www.colby.edu/chemistry/OChem/
Electron Configurations Quiz 1
1. Write the full electron configuration & draw the
     atom for nitrogen, N – atomic number 7,
     atomic mass 14.01.
2.   Write the full & Noble Gas electron
     configurations for nickel, Ni – atomic number
3.   Identify the element with the Noble Gas
     electron configuration of [Ar]4s23d6.
     Explain how you know.
Electron Configurations Quiz 2

1. Write the electron configuration & draw
   an atom of oxygen.
2. Write the complete and Noble Gas
   configurations for arsenic, As.
3. Identify the element that approximately
   matches [Xe]6s25d104f146p2 & explain
   how you know.
Periodic Table Activity
  Thursday 11/29/07
1. Grade fireworks posters.
DMA: What principle determines which elements are in the same vertical column?
Due: Page 163,173,185, Fill in blanks?
1.     Fill in blanks Periodic Table, 1 part at a time
2.     Notes on Development of Periodic Table
Asmt: Shade sections of 9 overlapping sections of Periodic Table (pages 164-7)
1.     Finalize POD meeting plans & Sliding Scenario pieces.
2.     Grade Fireworks posters.
DMA: Electron Configurations Quiz 2
1.     Grade Quiz
2.     Periodic Table Card Puzzle
Asmt: Asmt: Shade sections of 9 overlapping sections of Periodic Table (pages 164-7)
After School:
1.     Grade fireworks posters
2.     Thursday chores at home plus piano practicing.
3.     Left overs, chips to Men’s group.
Development of the Periodic Table (1 of 2)
• Periodic Law – When elements are
  arranged in increasing atomic number,
  their chemical & physical properties show
  a periodic pattern.
• Dobereiner grouped the elements into
  triads with similar chemical properties.
• Newlands arranged the elements by
  increasing atomic mass and observed the
  Law of Octaves where elements of similar
  properties occurred every 8th element.
Development of the Periodic Table (2 of 2)
• Mendeleev arranged the elements by increasing
    mass & similar properties in 1872.
•   Mendeleev suggested that atomic masses that
    were out of line with the similar properties
    needed to be remeasured.
•   Mendeleev accurately predicted the existence
    and properties of elements yet to be discovered.
•   Moseley discovered a pattern in the spectral
    lines of elements which corresponded to the
    atomic number and number of protons.
Periodic Table Patterns

• http://www.sciencebyjones.com/periodic_t
• http://environmentalchemistry.com/yogi/p
• Can use the one above to find the
  patterns & then explain them.
Observing Element Samples

1. Use your blank periodic table with trends
   of electron configurations.
2. Observe 2 samples from each of the 9
   sets around the room.
3. For each sample, record the symbol in
   the correct box plus 2 words to describe
   the appearance of the sample.
Monday 12/2/07

• Periodic trends – atomic radius, ionization
  energy, electronegativity
• Analyze data & graphs, Explain trends
Patterns of Electron Configurations

Vertical Patterns        Horizontal Patterns

Same number and type     Same kernel across
of valence electrons.
Energy level rises for   The kernel is the
each row.                previous noble gas
                         Highest energy level is
                         the same across a row.
Patterns of Electron Configurations

• Vertical Patterns          • Horizontal Patterns
• Same number and            • Same kernel across
    type of valence          • The kernel is the
    electrons.                   previous noble gas
•   Energy level rises for   •   Highest energy level
    each row.                    is the same across a
                 Periodic Patterns
    s1                                        s2p6
    H.    s2        s 2p1 s2p2 s2p3 s2p4 s2p5 :He

  . X :Be                   .. ..
                    :X. :C :N :O. :F: :Ne:

                                                                     : :: :
                                .    ..   .
                    . Al . X. . X. . X: : X. : X :

                                                         : :
          X                      .


     +1     +2          +3   +4          -3         -2          -1

                                                          : :
                                              : :
                                   : :
   [x] [x]           [x]     -4   [:x:] [:x:] [:x:]
Ion formation: Loss (oxidation) or gain (reduction) of electrons
Periodic Trends
• Trends in atomic radius, ionization energy, &
    electronegativity are determined by:
•   The number of energy levels present.
•   The attraction between the positive nucleus and
    the outer shell electrons.
•   Interfering “shielding” by electrons on inner
•   How close an atom is to completing the stable
    octet of outer “valence” electrons.
Atomic Radius (1 of 3)

• Alkali metals are the largest atoms.
• Noble gases are the smallest atoms.
          Atomic Radius (2 of 3)
Atomic radius
1) Atomic radius
   down a group
   or column.
2) Atomic radius
   across a
   period or row.
       Atomic Radius (3 of 3)
How do we explain the trends?
1. Atomic radius increases down a group:
  •   Each row adds an energy level.
  •   Interior electrons interfere with attraction of
      valence electrons toward the nucleus
      “shielding effect”
2. Atomic radius decreases across a row
   even while the atomic number increases:
  •   While in the same energy level, the nucleus
      becomes more positive & attractive.
• Ionization – Removal of electrons produces +
    charges & shrinks radius.
•   http://hogan.chem.lsu.edu/matter/chap26/anim
•   Animated Ionizations Change Radii Across
    periodic table.
•   http://www.chem.iastate.edu/group/Greenbowe
         Ionization Energy (1 of 4)
• Ionization energy is
    the energy required
    to remove a
    negative electron
    and leave an atom
    with a positive
    charge – as an ion.
•   Occurs in solar
    cells, geiger
    counters & smoke
    detectors with
    Amerecium 241
       Ionization Energy (2 of 4)

• Alkali metals lose their electrons most easily.
• Noble gases hold their electrons most tightly.
Ionization Energy (3 of 4)

                  • Removing an
                      becomes more
                      difficult across
                      a row.
                  •   Removing
                      becomes easier
                      down a column.
        Ionization Energy (4 of 4)

• Removing electrons is more difficult across a
    row as the nuclear attractions become stronger.
•   Removing electrons is easier down a column as
    each additional energy level increases the
    distance from the nucleus and weakens the
    nuclear attraction.
•   Repulsive shielding by interior electrons also
    decreases the attraction for each added level.
        Electronegativity (1 of 3)
• Electro-
  negativity is
  the ability of
  an atom to
  that are
  shared in a
        Electronegativity (2 of 3)
• What are the trends in electronegativity?
Electronegativity (3 of 3)
                  • Electronegativity
                      increases up & to
                      the right.
                  •   This trend
                      corresponds to
                      attractions to the
                  •   Less shielding
                      effect strengthens
                      attractions to the
                      nucleus in upper
Periodic Patterns Quiz
Atomic Radius Question – What is the size
  surprise? Why does it occur?
Ionization Energy – Why are the lowest
  ionization energies in the bottom left?
Electronegativity – Arrange each set of
  atoms in order from least to greatest
  electronegativity: Mg, Ba, Sr; Cl, F, I; Fe,
  K, Br
Periodic Patterns of Reactivity

• Choose an element from the periodic
• Predict how you think it will react with air,
  water, acids or bases.
• Observe the laserdisc video.
• Record the reactivity on a 1R-10R scale.
• Examine no more than 3 per group.
• Identify patterns of reactivity.
    Comparing Periodic Groups
 Group       Common      Common      Properties     Sources of 2 –        Uses of 2
              Valence      Ionic                    How obtained         elements of
             Electrons   Charges                                            Group
  Alkali        S1         +1       Soft metals,    Electrolyze salts   Na – table salt
                                   Explode in H2O                        K - gatorade







     Comparing Periodic Groups
Group        Valences   Ions,              Properties      Sources of 2 –       Uses of 2
                        # of Bonds                         How obtained         elements min

Alkali       S1         +1, ionic          Soft metals,    Electrolyze salts    Na – table salt
                                           explosive                            K – gatorade
Alkaline     S2         +2, ionic          Soft, highly    Electrolyze salts    Ca – bones,
Earth                                      reactive                             Mg – flash bulbs
Transition   S2d1 –     Various charges    Hard metals,    Mined &              Iron in steel,
             s2d10      +2,+3, +4          w/ varying      extracted from       Gold jewelry
                                           resistance      ores
Boron        S2p1       +3, (or 3 bonds)   Nonmetals &     Extracted from       Al - cans
                                           metals          bauxite ore
Carbon       S2p2       + or – 4, 4        Nonmetals to    Common in life,      C – pencils, Si –
                        bonds              metals          rocks & ores         chips, Pb – wts
Nitrogen     s2p3       -3, 3 bonds        Non-metals,     N from air, P from   Fertilizers
                                           semi-metals     phosphates
Oxygen       S2p4       -2, 2 bonds        Non-metals to   O from air, S        Breathing, make
                                           metals          mined                sulfuric acid
Halogens     S2p5       -1, 1 bond         Reactive        Electrolyze salts    Cl – bactericide
                                           Nonmetals                            F - toothpaste
Noble        S2p6       0, 0 bonds         Unreactive      Isolated from air    He – balloons
Gases                                      gases                                Ar – light bulbs

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