Catalyst 9/6/13
On your Catalyst Sheet, please answer the
following questions:
1. What happens to electronegativity (EN) or
ionization energy (IE) as you go across a period?
2. Sort from lowest to highest IE: Ba, Be, Ca
3. Sort from highest to lowest EN: P, Ge ,O
Announcement #1
• Homework 1.9 – Periodic Trends due
TUESDAY
Announcement #2
TURN IN YOUR COIN
DENSITY LAB REPORT (if you
haven’t already)
Deadline for credit: Monday 9/9
(Periods 1/3/5); Tuesday 9/10
(Periods 2/4)
Announcement #3
• UNIT 1 EXAM NEXT MONDAY (9/9) OR
TUESDAY (9/10) (WRITE DOWN IN
AGENDA)
• COVERS EVERY LEARNING TARGET IN
THIS UNIT (1.1 – 1.9)
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1.1 Intro to the Atom
1.2 Development of Atomic Theory
1.3 Periodic Table
1.4 Bohr Models
1.5 Element Families
1.6 Metals/Semimetals/Nonmetals
1.7, 1.8, 1.9 Ionization
Energy/Electronegativity/Atomic Radius
Lecture 1.8 – Electronegativity
Today’s Learning Targets
• 1.8 – I can define electronegativity and explain
how it relates to the charge of the nucleus and
the electron. I can explain how this trend
changes as you move throughout the Periodic
Table.
What is electronegativity?
I. Electronegativity
• Electronegativity (EN) is the measure of the ability
of an atom to attract electrons.
What are the trends for
electronegativity?
I. Electronegativity Trends
• As you go down a group, the electronegativity
decreases.
• As you go across a period, the electronegativity
increases.
Class Example
• Order the elements from smallest to largest
electronegativity: oxygen, beryllium, lithium,
Table Talk
• Order the elements from largest to smallest
electronegativity: chlorine, bromine, fluorine
Stop and Jot
• Order the elements from smallest to largest
electronegativity: silicon, aluminum, sulfur
Why do these trends exist?
I. Why Electronegativity Decreases Down a Group
• As you go down a group more orbits are added.
• EN decreases because the nucleus cannot attract
electrons as well due to the larger distance.
II. Why Electronegativity Increases Across a Period
• As you move across a period you add more protons
and electrons within the same orbit.
• The larger amount of protons in the nucleus and
electrons in orbit show an increased attraction,
which leads to increased EN
White Board Races
Directions
• The 5 people in your team are the line of people in front
and/or behind you
• The front person in each team will answer the 1st
question on the whiteboard
• Once the first person shows me a correct answer, he or
she will pass it back to the second person to answer the
2nd question
• The process repeats with the board being passed back
• For the 5th question, if you only have 4 people the last
person has to run the board up to the person in front
• NO HELPING TEAMMATES
Relay Race Problems
1. Which has a larger electronegativity: chlorine
or silicon?
2. Which has a smaller electronegativity
magnesium or calcium?
3. Put the following elements in order from
smallest electronegativity to largest: B, F, N, O.
4. Put the following elements in order from
smallest electronegativity to largest: N, As, Bi, P
.
5. Why does bromine do a worse job of attracting
electrons than fluorine?
Tug of War
Justify – TPS
• Explain why there was a difference between the
nucleus and electron groups’ ability to win
• What happened to the rope as more people were
added to the “nucleus”?
Lecture 1.9 – Atomic Radius
Today’s Learning Targets
• 1.9 – I can define atomic radius and explain how
it relates to the charge of the nucleus and the
electron. I can explain how this trend changes as
you move throughout the Periodic Table.
What is atomic radius?
I. Atomic Radius
• Atomic Radius – The distance from the center of
the nucleus to the edge of the electron cloud
Outer edge of
electron cloud
Nucleus
What are the trends for atomic radii?
I. Atomic Radius Trends
• Atomic radius increases as you go down a group
• Atomic radius decreases as you go across a period
Why do these trends exist?
I. Why Atomic Radius Increases Down a
Group
• As you go down a group, more orbits are added.
• The atom becomes bigger in size and so the
radius increases.
II. Why Atomic Radius Decreases
Across a Period
• As you move across a period, more protons are
added to the nucleus.
• This means there is a larger nuclear attraction and a
decrease in the radius.
SUMMARIZE
Pick a Side
• I am going to project up numerous statements
• You must decide whether you agree or disagree.
• Failure to participate, excessive talking or
touching will result in consequences
• Be prepared to defend your response!
Pick a Side Questions
1. Atomic radius is the distance from the center
of the nucleus to the first electron orbit.
2. Atomic radius increases across a period and
down a group.
3. Atomic radius decreases down a group because
you are adding more electron orbits.
4. Atomic radius decreases across a period
because there are less electrons in the same
orbit.
Pick a Side Questions (cont.)
5. Order the following from largest to smallest
atomic radius: Ca, Se, Ni
- Answer: Se, Ni, Ca
6. Order the following from largest to smallest
atomic radius: O, Po, S
- Answer: O, S, Po
7. Order the following from smallest to largest
atomic radius: Cs, F, Ga
- Answer: F, Ga, Cs
Putting it All Together!
• With your table, create a Venn
Diagram of the 3 Periodic Trends
that we have been studying
(ionization energy, electronegativity,
atomic radius)
• Your Venn Diagram must include:
– The trend as you go across a period
and down a group.
– The definition of each trend
– How nuclear attraction impacts each
trend
– How the number of orbits impacts
the trends
– An example, using elements, of how
each trend changes across a period
and down a group.
Exit Ticket
1. Define any two of the following:
Ionization energy
Electronegativity
Atomic radius
2. Order from largest to smallest electronegativity:
Ca, Se, Ni
3. Order from smallest to largest atomic radius: O,
Po, S