1. No category

One Stop Shop For Educators
The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples
of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using
the Search Standards feature located on GeorgiaStandards.Org.
Georgia Performance Standards Framework for Science – Chemistry
Introduction
Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
Unit Framework Annotation
This unit, Finding Patterns, takes an inquiry approach to understanding the patterns of properties that
exist among the elements. These patterns in properties are then linked to the wave-mechanics concept of
atomic structure and the quantum atom. Beginning with isotopes and average atomic mass, as a way of
understanding the importance of the atomic number in the identity of an element, the unit then uses the
periodic table, as the ultimate graphic organizer for our knowledge of atomic structure and properties.
The trends (patterns) of the periodic table are then connected to electron configuration.
The skills involved in this unit include: calculating average atomic mass of isotopes; graphing and
analyzing data for the trends of the periodic table; writing and analyzing electron configurations;
describing periodic trends; conducting flame tests to identify elements; performing mole/mass
conversions.
Understanding how the body of scientific knowledge has developed through the work and insights of
many scientists is central to this unit.
The activities and tasks are suggested but should be adjusted, omitted or enhanced as needed for specific
class situations. Some classes may need more time, practice, or instruction for some concepts. Others
may need less. For these reasons, the number of days required may need adjustment.
› Note on safety: Review and require students to follow all appropriate lab safety rules,
including the wearing of goggles and aprons, fire safety, clothing safety and the safe handling
of chemicals. Students must be thoroughly knowledgeable about the use of safety equipment
including the shower, eyewash, sinks, and fire extinguisher.
Approximate Duration for the Unit Framework
3 – 4 Weeks
Standards
Focus Content Standards
SC2. Students will relate how the Law of Conservation of Matter is used to determine
chemical composition in compounds and chemical reactions.
SC2c. Apply concepts of the mole and Avogadro’s number to conceptualize and calculate mass, moles
and molecules relationships.
SC3. Students will use the modern atomic theory explain the characteristics of atoms.
SC3b. Use the orbital configuration of neutral atoms to explain its effect on the atom’s chemical
properties.
SC3d. Explain the relationship of isotopes to the relative abundance of atoms of a particular element.
SC3f. Relate light emission and the movement of electrons to element identification.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 1 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
SC4.Students will use the organization of the Periodic Table to predict properties of elements.
SC4a. Use the Periodic Table to predict periodic trends including atomic radii, ionic radii, ionization
energy, and electronegativity of various elements.
SC4b.Compare and contrast trends in the chemical and physical properties of elements and their
placement on the Periodic Table.
Integrated Characteristics of Science Standards
SCSh1a,b,c. Students will evaluate the importance of curiosity, honesty, openness, and skepticism
in science.
SCSh2a,b,c. Students will use standard safety practices for all classroom laboratory and field
investigations.
SCSh3a,b,c,d,e,f. Students will identify and investigate problems scientifically.
SCSh4.a,b. Students will use tools and instruments for observing, measuring, and manipulating
scientific equipment and materials.
SCSh6a,b,c,d. Students will communicate scientific investigations and information clearly.
SCSh7a,b,c,d,e. Students will analyze how scientific knowledge is developed.
Students will recognize that:
a. The universe is a vast single system in which the basic principles are the same everywhere.
b. Universal principles are discovered through observation and experimental verification.
c. From time to time, major shifts occur in the scientific view of how the world works.
More often, however, the changes that take place in the body of scientific knowledge
are small modifications of prior knowledge. Major shifts in scientific views typically
occur after the observation of a new phenomenon or an insightful interpretation of
existing data by an individual or research group.
d. Hypotheses often cause scientists to develop new experiments that produce additional
data.
e. Testing, revising, and occasionally rejecting new and old theories never ends.
SCSh8. Students will understand important features of the process of scientific inquiry.
Students will apply the following to inquiry learning practices:
a. Scientific investigators control the conditions of their experiments in order to produce valuable data.
b. Scientific researchers are expected to critically assess the quality of data including
possible sources of bias in their investigations’ hypotheses, observations, data analyses,
and interpretations.
d. The merit of a new theory is judged by how well scientific data are explained by the new theory.
e. The ultimate goal of science is to develop an understanding of the natural universe
which is free of biases.
f. Science disciplines and traditions differ from one another in what is studied, techniques used,
and outcomes sought.
Complementary Standards
SC1a Relate the role of nuclear fusion in producing essentially all elements heavier than hydrogen.
SC1b Identify substances based on chemical and physical properties
SC3 Students will use the modern atomic theory to explain the characteristics of atoms.
SC3a Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in
the atom.
SC3c Explain the relationship of the proton number to the element’s identity.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 2 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Understanding and Goals
Unit Understandings, Themes, and Concepts
Atomic theory has been built on the measurements, observations, discoveries, and interpretations of data
by many scientists, and has been modified over the centuries by both major discoveries and small
modifications until today our current understanding of atomic structure is best explained by the wavemechanics model. This understanding unites the understandings of Unit One, Finding Order, with this
unit, Finding Patterns, and is a unifying theme of chemistry.
•
•
•
•
The modern atomic theory provides an explanation for the many patterns found in the properties of
the elements, including atomic number, electron arrangement, reactivity, and bonding,
The periodic table, arranged by atomic number, reveals a tendency for properties to repeat in a
periodic pattern (periodicity), and can be used to predict the properties and uses of an element.
These periodic trends exist for many properties of the elements including atomic radii, ionization
energy, and electronegativity.
Although different numbers of neutrons exist in different forms (isotopes) of the same element, it is
the number of protons that determines the atom’s identity. Average atomic mass reflects the relative
abundance of these isotopes.
Complementary Understandings introduced in the unit, Finding Order
• Order is inherent in the structure of matter.
• Matter is composed of a limited number of elements.
• Elements were created through nuclear events in the universe.
• All matter possesses physical and chemical properties that are related to its atomic structure.
• Measurement is an important means of understanding matter.
• The fundamental unit for measuring amount of substance is the mole.
Essential Questions
• What does electron arrangement have to do with fireworks?
• How does average atomic mass reflect the relative abundance of the isotopes of an element?
• How is molar mass related to atomic mass?
• In what ways does the periodic table organize what we know about the elements?
o What trends in chemical and physical properties are revealed by the periodic table?
• How has the periodic table been amended over the years to reflect new understandings of atomic
structure?
• How are electrons arranged in energy levels, sublevels, and orbitals outside the nucleus?
• How can electron arrangement be used to identify substances?
o How can flame tests be used to identify metals?
Misconceptions that this unit addresses:
Students may have naïve or erroneous ideas about atomic structure including:
• the misconception that all atoms of the same element are identical
• the misconception that electrons orbit the nucleus in fixed paths
• the misconception that the more mass an atom has the larger it is
the misconception that the elements always exist in nature in their atomic form.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 3 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Language to use: atomic number, electron configuration; orbital; isotope; mass number; average
atomic mass, electron dot, ionization energy, electronegativity, atomic radius, emission spectrum, octet,
period (series), family(group), periodic table, alkali metals, alkali earth metals, transition metals,
nonmetals, metalloids, halogens, noble gases, inert, mole
Balanced Assessments
Method/
types
Informal
Observations
Dialogue and
Discussion
Selected
Responses
Constructed
Responses
Self-Assessments
Average
atomic mass
calculations
Monitor and
conference
with groups on
“Organizing
the Elements
Lab”
Oral
questioning
during
Organizing
Elements Lab
& Periodic
Trends Lab
Items on
unit test
Organizing
Elements Lab
Check electron
configuration
Items on
electron
configura-tion
quiz
Flame test lab
report
Group
coaching
occurs in
Organizing the
Elements Lab
(peer
assessment)
Monitor for
understanding
as students
graph trends
Silent
roundtable
task
Discussion/
overview of
periodic trends
Identifying
mystery
elements
(based on
various
properties)
Check for
Check electron understanding
configurations the nature of
the mole
Tickets out the (taught in
door for
Unit, Finding
electron
Order)
configuration,
orbital
notation, and
Lewis dot
structure
Draw an atom
(formative)
Graph trends
of the periodic
table
Electron
configuration,
orbital
notation and
Lewis dot
structure work
The Periodic
Table
Salesman
GRASP
Assessment
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 4 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Unit Performance Task(s)
Unit Performance Task Title
Two alternatives are given here for the unit performance task. Choose one of these, or differentiate, or
design your own.
Research project on Modern Lighting:
Suggested use: This may be a culminating activity after the students have had experience with and
explanation of spectrum tubes, flame tests, and emission spectra. The format might be a choice of
written report, multi-media presentation, or demonstration with commentary. This may be done
individually or it could be organized in groups of four, where each member is responsible for one type
of lighting, (incandescent, fluorescent, inert gas, halogen), but the presentation is a group effort. For
each type of lighting, the student should explain how the light produced is related to the emission of
light energy from the movement of electrons in the atoms.
Develop a rubric that is consistent with the intended outcomes.
GRASPS Activity: TOXITOWN
After the student learns and practices the technique for conducting flame tests on a set of metallic ions,
present the following GRASP scenario along with samples of the suspicious leakage.
A new subdivision is being constructed in Toga County, just south of the old landfill on the edge of
Toxitown. Last week several leaking containers were unearthed by a crew clearing land for a new
home.
Goal: To use appropriate science process skills to identify a substance by its chemical properties.
Design and carry out a protocol for an initial analysis of the materials found in the containers to
incorporate methods you have already learned. Investigate other methods for identifying elements or
compounds.
Roles: You are chemist working for the State Environmental Monitoring Agency (SEMA). You are a
member of a team that consists of a project manager, a technology coordinator, a research analyst, and a
senior chemist. You must agree on who has each role, but the work must be equally shared.
Audience: The county commissioners of Toga County, Toxitown city council members, concerned
citizens, and reporters from the Toxitown Tabloid.
Situation: (Scenario) Your agency has been hired to test the questionable material and report the
findings. The findings will be presented to the elected officials at a public community meeting.
Product: The presentation should include your research, procedures, data, and analysis. This
information should be presented both orally and graphically and as a written executive summary of the
data and analysis. Appropriate technology should be used. Additionally, the report should address the
limits of this analysis and suggest further tests that should be considered, explaining the type of test and
what information could be obtained from the tests.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 5 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Standards: SC3f, SCSh1a,b,c;SCSh2,SCSh3;SCSh4;SCSh6;SCSha,b
ƒ
Teacher Note: Choose an element that was included in the lab to build your story around.
For example, you could include lithium chloride in the unknown solution. The color will
be easy to detect in a flame test, and the students will discover that it has been used in
treating certain mental illnesses when they begin to research the compound. This will give
the students something to analyze in terms of safety, disposal and industrial responsibility.
They can also determine how easy or hard it will be to dispose of the containers.
Rubric for Performance Task
Not included; rubrics should be designed by the teacher and based on the elements that are being assessed.
Student Work Sample with Teacher Commentary
(To be added as available)
Web Resources
Sample List of Appropriate Resources for Unit: Finding Patterns
A Science Odyssey: "Mysteries of the Universe" video produced by WBGH.
A brief excerpt, from the video, related to modern atomic theory leading up to the advent of the
quantum atom model and nature of the electron, can be found at:
http://www.teachersdomain.org/9-12/sci/phys/fund/quantum/index.html. Site registration
required, but free.
Origins, A NOVA Presentation: "Back to the Beginning", produced by WGBH.
“The Elements Forged in Stars”, a fast paced excerpt from the video, discusses/depicts the stellar
events as samples of the elements are placed on the periodic table.
http://www.teachersdomain.org/9-12/sci/ess/eiu/fusion/index.html.Site registration
required, but free.
www.keypress.com/chemistry/downloads/SampleLessons
Re: periodic table lesson plansteachers.net/mentors/science/topic5162/6.30.06.17.36.16.html
Teachers' Domain: Periodic Table of the Elements chart
http://chemistry.about.com/od/fireworkspyrotechnics/
http://www.ci.natchitoches.la.us/Festival/Fireworks.asp
http://www.sandlingfireworks.com/index.html
http://chemlab.pc.maricopa.edu/periodic/spiraltable.html
http://www.periodictable.com/pages/AAE_3d.html
http://chemistry.about.com/cs/howthingswork/a/aa060601a.htm
http://www.avogadro.co.uk/light/bohr/spectra.htm.
http://www.oedilf.com/db/Lim.php?Word=Balmer%20series
http://www.afn.org/~afn02809/
http://www.oakton.edu/user/~mwalter/playdoh/Gordon_Conference_Poster_5.htm
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 6 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
PERFORMANCE TASKS FOR LEARNING AND ASSESSMENT
SC3-2 KWL: What do we know, need to know, and what did we learn about atomic structure?
Suggested use: This task can be used In this unit the task is repeated after instruction on the
wave-mechanics model of the atom to introduce the unit and revisited and completed as the unit
unfolds.
Draw an Atom Learning Task:
This task was begun in the Unit, Finding Order; in this unit, this task is repeated after instruction
on the wave-mechanics model of the atom. Direct students to draw what they think an atom
looks like. On the first day of learning about atomic structure, the student will make this drawing
in his/her notebook along with the date. Along with the drawing, the student will give a written
explanation of what they understand about the structure of the atom at this time. This activity
will be repeated at appropriate intervals as the unit progresses and understanding increases. SC3;
SCSh7c; SCSh8d.
This activity is useful for activating thinking at the beginning of the lesson and for teacher
monitoring for understanding and formative assessment. Student drawings and writings usually
reveal misconceptions. The teacher can see what these misconceptions are, and incorporate
instruction to address them.
Average Atomic Mass Analogy
Tell students that you have been looking at a particular classmate’s grades for this grading
period. The student has nine grades of 95, and one grade of 10. If all grades count equally, what
is this student’s average as of today? Allow students to calculate and explain their calculations.
Then lead them to understand that 90% of the grades have a “grade mass” of 95, and 10% of the
grades have a “grade mass” of 10. The average grade “mass” would be 86.5.
Probe with questions such as, which grade has the most effect of the grade?
Teacher Note: Students will usually take both sides in this discussion. This discussion will lead
into the concept of relative abundance.
Next have them calculate the grade if eight grades are 95.0, one grade is 94.5 and one grade is
94.1. Repeat the discussion and lead into average atomic mass of an element.
Teacher Note: This task is effective as an activating strategy that leads directly into the
teaching of average atomic mass.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 7 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Average Atomic Mass Modeling Task
Student groups use colored paper clips to represent pro-clips and neu-clips to build models of the
three isoforms of clippium and record their relative mass. Each paper clip has a relative mass of
one pcmu paper clip mass unit (pcmu). Clippium-1 has a clip mass of 1.0(one pro-clip).
Clippium-2 has a clip mass of 2.0(one pro-clip and one neu-clip), and clippium-3 has a mass of
3.0 (one pro-clip and two neu-clips).
After constructing these isoforms, give students the relative abundance of these isoforms (make
these up; for example, the sample could be 95% Clippium-1; 3% Clippium-2; 2% Clippium-3).
Have students calculate the average mass of the sample of clippium. Remember to address the
issue of significant figures.
(.95 * 1.0) + (.03 * 2.0) + (.02 * 3.0) = 1.07= 1.1 pcmu
Give students the relative mass data for the isotopes of hydrogen, or other elements, and have
them calculate the average atomic mass of the element. Relate this to molar mass of the element.
(also relates to SC2c)
Teacher note: This information is available in most chemistry texts as well as chemistry
reference books.
Wintergreen Mint Activity
This is a fun activity with a connection to the emission of energy as electrons fall to lower levels,
and a mini-lesson on lightning! Check the web for more information. One source:
http://chemistry.about.com/cs/howthingswork/a/aa060601a.htm
Create the Periodic Table Activity
There are various versions of this activity available from commercial and educational sources.
However, it is easy to create your own unique version. Cover or remove all visible copies of
the periodic table before beginning this activity. Prior to class create the element cards (a la
Mendeleev). The set should contain sequences of elements from chosen groups (families), i.e.
1,2,17,18. On each card write the symbol, name, atomic number and selected properties of the
element, but be sure that there is no indication on the card as to group. Include properties
such as melting point, reaction with acids, and bases, metal/nonmetal, and atomic radii. Give a
set of the cards to each collaborative group. The overall goal is to have the groups organize the
elements into logical patterns based on the properties of the elements given on the cards. After
arranging the elements, the group should conference with the teacher. During this conference, the
students explain their arrangement. If the arrangement is logical and shows trends, then they can
tape or glue their cards onto a larger sheet of paper to “create” their periodic table. Each group
member must be able to explain the reasoning for the arrangement. Each group then shares their
periodic table with the class. The teacher uses strategies to keep everyone engaged. For example,
cut a deck of real playing cards for high (or low) card to determine who will report for the group.
Group members should coach one another on their presentation, making sure that each member
is capable of explaining their arrangement since any member of the group may be called upon to
be the presenter, based on the luck of the draw. This strategy promotes peer coaching.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 8 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Alternative 3-D Graph of Periodic Trends Task
Create an alternative three dimensional periodic table that satisfactorily illustrates the periodic
properties of the elements. Use the 96 well-plate as a base to support drinking straws. Have
students determine a reasonable scale for the length of straws to correspond to the needed values
for atomic radii. For example, 1cm represents 1pm. Cut the straws to the appropriate length for
each element in an assigned period of elements. Place straws in sequence in the well plate to
create a 3-D graph of the trend. Repeat this process for ionic radii, ionization energy, and
electronegativity.
Also, if students have access to graphing calculators, graphing this data and tracing across the
min and max to see trends within a family and across a period is an effective summarizing
strategy.
Element Survey Lab
Students examine samples of elements representative of the element families and record
properties on a blank periodic table chart. After completing this observation and data collection,
students discuss patterns in the properties that they have discovered.
Teacher note: Elements should be in closed vials. Sets can be assembled and used year after
year.
Periodic Table Language Analysis Diagrams
The following diagram can be adapted for previewing or developing any language term or
concept.
Following the first diagram there are three that are specifically designed for this task.
TERM
Ter
AAAAAAAA
AtomicA
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 9 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Trend across a period
and why?
Trend down the group
and why?
Atomic
Radius
What is it?
Exceptions?
Trend down the group:
Explain.
Trend across a period:
Explain.
Ionization
Energy
What is it?
Exceptions? Explain.
Trend down the group:
Explain.
Trend across a period:
Explain.
electronegativity
What is it?
Exceptions? Explain.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 10 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Element Silent Roundtable Task
This task is an example of an activating, team-building strategy. Each student will write with a
different color marker. When instructed to start, one member of the group will write the name of
an element on the board, then pass it to the right. Each member of the group will add one
element to the list, then pass it on to the next member. If a member cannot think of an element,
that member must think for at least 10 seconds before passing the board on. Continue to do this
without talking, until the group cannot think of additional elements.
Debrief: List the teams’ names across the top of a blackboard. Call on each group to offer one
element. As each element is listed, other groups check it off. Each element that a team gets on
the board is worth one point. Start each round with a different group, in order to give each group
the advantage of going first. Groups may also challenge each other. (A common error is that a
team will list an alloy or compound instead of an element.) If a challenge is correct, the
challenging team gets the point. If the challenge is wrong, the team loses one point. If a team is
not paying attention, and names an element that is already on the board they lose one point.
Points can be used as bonus points for the team members with every student getting the total
team points divided by the number of team members.
A variation on this task is to repeat it using symbols rather than the names after students have
been using the symbols in the context of the course, or after being assigned specific symbols to
learn.
Teacher notes:
1. White boards can be made by cutting a piece of white shower board from a building supply
company into squares with a table saw. Alternatives are laminated card stock or simply use a sheet
of paper!
2. This activity might be extended as a review activity at the end of the unit from just producing
names and/or symbols to grouping elements by family, solid/liquid (a very short list)/gas,
reactivity within a family, atomic radii or other trends.
The Periodic Table Salesman ( Selling The Ultimate Graphic Organizer)
This is a GRASP task for the Finding Patterns Unit
Goal: Explain the power of the periodic table to organize chemical information and predict the
behavior of matter.
Role: You are a periodic table salesman
Audience: A physical science teacher
Situation: The teacher has a limited budget and must choose between ordering beakers or a large
periodic table for the classroom wall which comes with a set of activities for understanding the
periodic table.
Product: Produce a brochure, multimedia presentation, or a letter to remind the teacher of all the
ways that the periodic table is the ultimate graphic organizer for understanding chemistry.
Include the trends covered in class and how the teacher and students can make use of this
information.
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 11 of 12
Copyright 2006 © All Rights Reserved
One Stop Shop For Teachers
Georgia Performance Standards Framework for Science – Chemistry
Mystery Element Task
Each student will pick one element a write a description of it using the physical properties. This
description can be extended to include researched characteristics, not immediately evident from
this observation lab. Students write their descriptions on index cards or squares of paper. The
description could be written as a riddle or a poem. (Haiku or diamante are interesting variations
for the class literati.) If the class is working in groups, the sets of cards can be passed from
group to group to be answered for practice. This is a good formative assessment opportunity.
Balmer Series Limerick: Note from the referenced website: “We welcome efforts by others to
spread the word about the OEDILF. If you choose to reproduce a limerick from our dictionary
under the doctrine of fair use, we require that you credit the limerick's author.”
Balmer series, Balmer, Johann by mike scholtes
Stars' spectra show shadows in series;
Hence Balmer directed his queries
To the spacing of lines
Caused when hydrogen shines,
Which led Doctor Bohr to his theories.
Johann Balmer (1825–1898) discovered a simple mathematical relationship that governs the
wavelengths of hydrogen absorption (and emission) lines. This relationship was later explained
by Niels Bohr's atomic theory, in which a hydrogen atom's one electron can occupy discrete
energy levels. Bohr's theory led to the current quantum mechanical theory. The series
corresponding to electrons leaving or returning to the ground state (n=1) is called the Lyman
series, but its wavelengths are all in the ultraviolet. The Balmer series corresponds to electrons
leaving or returning to the (n=2) energy level, and its lines are prominent in the visible-light
spectra of most stars.
Cooperative test questions: This activity gives students an investment in the test items and is a
team building strategy. The teacher tells class that some of the items they write will be included
on the test. If a student’s question is chosen, five (or more) points will automatically be added to
the student’s test score.
Round one: Assign each group one essential question. Each student in the group makes up one
selected response (multiple choice) test item that addresses the group’s essential question and
writes the question on the front of an index card, and the answer on the back. The group
members then quiz each other, and make sure that they all agree and understand the answers.
Round two: Each group passes their cards to the next group and who then answer the new set of
questions.
Rounds three throughÆ: The process continues until the questions have traveled to each group.
To summarize the teacher takes up all cards and pulls some at random to ask to the class. (Use
the name beaker).
Georgia Department of Education
Kathy Cox, State Superintendent of Schools
Chemistry y Finding Patterns – Organizing Chemical Knowledge on the Periodic Table
October 2006 y Page 12 of 12
Copyright 2006 © All Rights Reserved