Periodic Trends Notes and
Practice
• Objective
– Today I will be able to:
– Analyze data to explain the trends of atomic radius, ionization
energy and electronegativity
– Apply periodic trends to solving problems
• Evaluation/ Assessment
– Informal assessment – Listening to group interactions and
discussions as they complete the periodicity practice
– Formal Assessment – Analyzing student responses to the
exit ticket and periodicity practice
• Common Core Connection
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Build Strong Content Knowledge
Reason abstractly and quantitatively
Look for and make use of structure
Look for and express regularity in repeated reasoning
Lesson Sequence
• Warm – Up
• Evaluate: Observing Trends – Data Analysis
– Informal assessment as students answer questions
– Formal assessment collecting responses
• Explain: Periodic Trends Notes
• Elaborate: Periodicity Practice Worksheet
– Informal assessment as students answer questions
– Formal assessment collecting responses
• Evaluate: Exit ticket
– Formal assessment
Warm - Up
• What is the electronegativity?
• What happens to electronegativity as you
travel across a period?
• What happens to electronegativity as you
travel down a group?
Objective
• Today I will be able to:
– Analyze data to explain the trends of atomic
radius, ionization energy and electronegativity
– Apply periodic trends to solving problems
Homework
• Periodicity Worksheet
• Periodic Table Exam
– Thursday, December 6th
Agenda
• Warm – Up
• Review Observing Trends Data Analysis
Activity
• Periodic Trends Notes
• Periodicity Worksheet
• Exit Ticket
Observing Trends – Data Analysis
Review
Periodic Trends Notes
Atomic Radius
Distance from the center of an atom to the
outermost edge of the electron cloud
Decreases going across a period (row)
Increases
down a
family
(column)
Atomic Radius
Why does this trend occur?
Decrease across a period (row)
As you move across a period, more protons exert a pull
on the electrons pulling them tighter, decreasing the
radius
Increase down a family (column)
As you go down a family you are adding additional
energy levels to put the electrons in
Adding energy levels makes the electron cloud larger
Atomic Radius
Ionization Energy
 Energy needed to remove an electron from an atom
 High ionization energy means atoms hold their electrons
very tightly (noble gases)
 Exactly opposite to atomic radius trend!
Increases going across a period (row)
Decreases
down a
family
(column)
Ionization Energy
Why does this trend occur?
Increase across a period (row)
As you move across there are more valance electrons,
making the atom more stable. The atoms do not want
to lose the electrons so it requires more energy to
remove them
Decrease down a family (column)
The electrons are farther away from the nucleus so
they don’t feel as attracted to the positive charge of the
nucleus. Therefore, they require less energy to remove
Electronegativity
The ability to attract electrons in a chemical
bond
Increases going across a period (row)
Decreases
down a
family
(column)
Electronegativity
Why does this trend occur?
Increase across a period (row)
As you move across there are more valance electrons,
making the atom more stable. The atoms want to
attract an electron to become stable.
Decrease down a family (column)
The electrons are farther away in the orbital from the
nucleus so it is more difficult for the positive nucleus to
attract another electron.
Why don’t noble gases have values for
electronegativity?
• Stable
• The outer shell is filled with 8 valance
electrons
• They do not need to attract another electron
Electronegativity
Complete Periodicity WS
Responses will be reviewed as a class
Exit Ticket
• Arrange the following elements in the
sequences of shortest radius to longest radius
– I, Cl, F, Br
– O, N, F, C