Going with the Trends:
PERIODIC TRENDS
Concept Presentation
Andrew Selvam – HS Chemistry OISE/UT
Instructors: Janine Extavour/Marty Zatzman
Outline of Presentation
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Curriculum Expectations
What do I need to know before?
Where does the concept fit?
Roadblocks and Misconceptions for Teachers and Students
(incl. Solutions and Activities)
Lesson Sequence (incl. Accommodations and A&E)
Applications to Real World
Period Trends War Game
References
Curriculum Expectations
(Ontario Ministry of Education)
SPECIFIC EXPECTATIONS
A1.5
Conduct inquiries, controlling relevant variables, adapting or
extending procedures as required, and using appropriate materials
and equipment safely, accurately, and effectively, to collect
observation and data.
A1.6
Compile accurate data from laboratory and other sources, and
organize and record the data using appropriate formats,
including tables, charts, graphs, and/or diagrams
A1.10
Draw conclusions based on inquiry results and research
findings, and justify their conclusions with reference to scientific
knowledge.
Curriculum Expectations
(Ontario Ministry of Education)
B1.1
Analyse, on the basis of research, the properties of a commonly
used but potentially harmful chemical substance and how that
substance affects the environment, and propose ways to lessen
the harmfulness of the substance or identify alternative
substances that could be used for the same purpose.
B2.1
Use appropriate terminology related to chemical trends and
chemical bonding, including, but not limited to: atomic radius,
effective nuclear charge, electronegativity, ionization energy, and
electron affinity.
B2.2
Analyze data related to the properties of elements within a
period (e.g., ionization energy, atomic radius) to identify general
trends in the periodic table
Review Items
• Grade 9 and 10 Science
– The Atom
• Composition of the Atom
• Subatomic Particle
– Formation of Ions
F
– Periodic Table
• Elements
• Features – Atomic Number and Atomic Mass
• Periods (Rows) and Groups (Columns)
of elements with similar properties
F  F1-
The Unit
• Periodic Trends is part of the first unit of SCH 3U
• Integral for students to understand the molecular/atomic
basis for the formation of compounds and the reaction of
those compounds (later in the unit)
Chapter 1
Observing
Matter
Chapter 2
Elements and
the Periodic
Table
Chapter 3
Chemical
Compounds and
Bonding
Chapter 4
Classifying
Reactions:
Chemicals in
Balance
Placement of Concept in the
Chapter
• The placement of the concept of the unit fits appropriately in
the context of the chapter
• Both McGraw-Hill and Nelson texts place the concept in the
following way:
Atoms, Elements and
the Periodic Table
Periodic Trends
(Involving the Sizes
and Energy Levels of
Atoms)
Classifying Chemical
Compounds
(Ionic vs. Covalent)
Why do you think this is?
The Concept
Atomic Radius
Ionization Energy
Effective Nuclear
Charge
PERIODIC TRENDS
Electron Affinity
Shielding Effect
Electronegativity
Reactivity
The Trends in Picture
Major Roadblocks for Teachers
Teachers have a two-fold problem when it comes to teaching
periodic trends:
1. Explaining (as opposed to simply memorizing) the subatomic basis
for all five trends
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Atomic Radius (Ionic Radius)
Ionization Energy
Electron Affinity
Electronegativity
Reactivity of Metals and Non-Metals
2. Looking for ways to help students retain
and review the knowledge of Periodic Trends
Misconceptions for Students
ROADBLOCK #1
• Visualizing attractive and repulsive forces between nucleus
and electrons
ROADBLOCK #2
• Understanding that the nucleus can have an ‘effective nuclear
charge’ and that inner-level electrons can shield the nucleus
from outer-level electrons
Ryan Seacrest shows Effective
Nuclear Charge with his smile!
The Solution to Misconceptions 1 and 2:
The Analogy with Atomic Radius
• Ryan
Seacrest =
Nucleus
• Mouthwash =
Effective
Nuclear
Charge
• Ladies =
Electrons
Using Desks in Your Classroom
Teacher’s Desk = Nucleus
= Electron
ROADBLOCK #3
Each periodic trend is really its own separate
concept. None of them are interconnected.
Visual: Across a Period…
Na
Mg
11P
12N
12P
12N
H
Li
Be
Na
Mg
Na
Mg
11P
12N
12P
12N
IONIZATION ENERGY
- It requires more energy to pull electrons
that have been tightly held by the nucleus,
therefore across a period, the ionization
energy increases
ATOMIC RADIUS
- Adding one proton increases the
charge of the nucleus to pull the
electrons towards them, therefore
across a period, the atomic size
decreases
ELECTRON AFFINITY/
ELECTRONEGATIVITY
- Because the electrons are being tightly
held by the nucleus, therefore across a
period, electron affinity and
electronegativity increases.
Visual: Down a Group…
Li
Na
3P
4N
11P
12N
H
Li
Be
Na
Mg
Li
Na
3P
4N
11P
12N
IONIZATION ENERGY
-It requires less energy to pull electrons
that are not tightly held by the nucleus,
therefore down a group, the ionization
energy decreases
ATOMIC RADIUS
- Going down a period, there are
additional energy levels to add to
the size of the atom, thus the
atomic radius increases
ELECTRON AFFINITY/
ELECTRONEGATIVITY
- The electrons are not being as tightly
held by the nucleus, therefore across a
period, electron affinity and
electronegativity decreases.
Each of you will receive two magnets:
Here are your instructions:
• Take a few minutes in pairs or in table groups to come up
with a way to use the magnets to explain a periodic trend
Now here is how you can use magnets to
show some of the periodic trends...
Using Magnets for Ionization
Energy
• Take two magnets. The first magnet is the nucleus and the
second magnet are the electrons in the outer shell.
• When the magnets are close together
– hard to pull them away from each other – requires more energy
• When the magnets are already far apart,
– it is easy to pull them further away, because of a weak force of
attraction
Lesson Day 1
Focus: Review of Atomic Composition and Atomic Structure
Activities:
- Chalk and Talk on Composition/Structure
- Demo 1: Atomic Emission Spectra
(Use Diffraction Gratings and Spectroscopes)
- Demo 2: Metal Reactivity (With Alkali Metals)
- Will Refer Back to Later in the Lesson Sequence
Accomodations: For IEP/ELL students, provide them with tables that give
them an idea of how the number of valence electrons relate
to groups on the periodic table
Assessment/Evaluation: Assessment for Grade 9 Review Items
Formative Assessment – Metal Reactivity Demo
Homework – Effective Nuclear Charge
Demo: Observing the Spectra of
Elements
H2
He
D2
Ne
N2
O2
Ar
Kr
Hg
Xe
Demo: Metal Reactivity
Li
Na
K
Metal Reactivity
increases as you
move down the
group.
Safety Precautions for Demo
• Lab not recommended for
students as it can be quite
violent
• Metals like lithium, potassium,
and sodium react violently with
air and so are kept in a special
mineral oil
• If you have a shield, put this up
to prevent injury or ask
students to move back
Lesson Day 2
Focus: Introduction to Periodic Trends
Activities:
- PowerPoint on Periodic Trends including Analogies
- VAK Activities:
- Magnet Analogy (Visual)
- Classroom Kinesthetic Activity
- Trends Exercise (Aural)
(Students can pair together to try activities)
- Discussion on Applications to the Real World
Assessment/Evaluation: Diagnostic Questioning – Previous Day Learning
Formative Assessment – Worksheet/Text Ques.
Formative Assessment – Exit Pass
Multiple Intelligences: Visual, Logical, Tactile, Interpersonal, Intrapersonal
Lesson Day 3
Focus: Reinforcement of Periodic Trends
Activities:
- Periodic Trends War Game (We will do this at the end!)
- Graphical Analysis of Periodic Trends
- Atomic Radius vs. Atomic Number
- Ionization Energy vs. Atomic Number
Assessment/Evaluation: Formative Assessment –
- Taking in Game Sheet for Periodic Trends War
- Taking in Graphs to get proof of student understanding
- Teacher will go around to help students one-on-one with
activity
Multiple Intelligences: Visual, Logical, Intrapersonal, Interpersonal
Graphic Resource for Periodic Trends
<http://www.teachersdomain.org/resource/l
sps07.sci.phys.matter.graphperiodic/>
Assessment & Evaluation:
KICA
Knowledge
Questions that ask to find the
element with the greatest or least
atomic radius, ionization energy
Inquiry
Questions that ask students to
explain the atomic basis for periodic
trends
Communication
Graphical analysis of periodic trends
Application
Discussion on uses of elements
based on their place in the Periodic
Table
Applications to the Real World
• Medical (Surgical)
– Because of the low
reactivity of Tantalum (Ta)
[bottom-left] of the PT, used
in surgical sutures, pins, and
implants
• Cooking
– Because fluorine is so
reactive it reacts with another
substance, and becomes
very stable. Teflon used in
pans is a combination of
carbon and fluorine.
More Applications...
• Industrial
– Tantalum oxide is used in
camera lenses
– Cesium (Cs) has a low
ionization energy and is
very reactive
– It is used in TV cameras and
traffic signals
– Chlorine and bromine are
used for sterilization (high
reactivity)
Periodic Trends War
• This is an adaptation of the card game ‘war’, except instead
of using playing cards, we will use index cards with an
element on it
• We will also use dice, where each face represents one of
the trends:
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1 – Atomic Radius/Ionic Radius
2 – Ionization Energy
3 – Electron Affinity
4 – Electronegativity
5 – Reactivity
6 – ‘Wild’ – Any of the trends above
Periodic Trend War Cont’d
Instructions:
1. Students get into groups of 3 or 4. Assign someone to be
the dealer.
2. The dealer will roll the die. Each student in the group will
reveal the element card from the top of their pile
3. It is now up to them to determine who wins the deal based
on who has the greatest value based on the trend
4. The person who wins becomes the dealer
Activity Assessment and
Evaluation
• Each student will get a game card
• The student will document the name of the trend, the
choices they had and the atom with the greatest value
• At the end of class, students will hand the game card in as a
formative assessment
• The teacher now has a better understanding of whether the
student knows the trend
Potential Advantage: Peer Collaboration
Potential Disadvantage: Peer Plagarizing
Text References
McGraw-Hill Chemistry 11
• Student Text and Teacher’s Resource
Addison-Wesley Chemistry 11
•Teacher’s Resource
Provides Suggestions for:
• Common Student Misconceptions
• Lesson Ideas for all Learning Styles
• Accommodations for Identified / ELL
Learners
• Assessment and Evaluation
• Possible Lab Investigations
Journal Articles
Montogomery, M. (2005). Periodic Table Trends. The
Science Teacher, 72(4), 50-51.
• This resource comes from a science teacher at a local
highschool in Southaven, Mississippi. The author attempts
to provide examples of how to demonstrate the trends of
atomic radius, ionic radius, and ionization energy by
reorganizing the desks in a classroom. He also tackles
concepts such as the shielding effect.
• Also goes into great explanations for ionic radii as well
Websites
Website: Howe, M., Krone, B., Reiter, S., and D. Verby.
Chemistry as Fun and Games.
<http://nobel.scas.bcit.ca/chemed2005/tradingPost/TUPM_S2_4_15C
hemFunGames.pdf.>
• Good resource for games that apply to concepts learned in Grade 11
and 12 Chemistry
YouTube Videos – Periodic Trends Song
<http://www.youtube.com/watch?v=MGTKVaZcq8Y>
• Cheesy song for students who might enjoy learning in the musical
genres of hip-hop and rap
Don't forget me!
Thanks for listening to my
presentation!
And thanks to Cora for all
her support!
If you ever thought
periodic trends could
not be cool, wait until
you listen to this
cheesy music video...