Catalyst 9/6/13On 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, Ca3. 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)– 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 Problems1. 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 Questions1. 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, Ca6. Order the following from largest to smallest atomic radius: O, Po, S

- Answer: O, S, Po7. 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 Ticket1. Define any two of the following:

Ionization energyElectronegativityAtomic radius

2. Order from largest to smallest electronegativity: Ca, Se, Ni

3. Order from smallest to largest atomic radius: O, Po, S