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) – 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 1 st 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 2 nd question The process repeats with the board being passed back For the 5 th 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