The document summarizes a chemistry lesson on periodic trends. It discusses the trends in atomic radius, ionization energy, and electronegativity across the periodic table. For atomic radius, it decreases from left to right and increases from top to bottom. Ionization energy increases from left to right and decreases from top to bottom. Electronegativity also increases from left to right and decreases from top to bottom. Examples are provided to demonstrate how to apply these trends to determine which atom has a larger/smaller value of the property. An exit slip quiz and homework assignment are assigned.

1. Launch
 Grab your binder and immediately take a seat
 Answer the following questions:
1. Using arrows, draw the trend for atomic radius.
2. Which atoms below have a larger atomic radius than
aluminum (Al)?
i) Cl iii) Si v) Na
ii) B iv) He vi) Ca

2. Weekly Schedule
 Monday: Atomic Radius
 Tuesday: Electronegativity & Ionization Energy
 Wednesday: Metals, nonmetals, special groups
 Thursday: Atomic structure & nuclear processes
 Friday: Mid-Term Exam
We don’t have much time!
If you don’t understand something, ask!

3. What is the trend in
ionization energy/
electronegativity?
Mr. Heffner
10/13/09

4. Ionization Energy
 Ionization energy is…
 how much energy it takes to steal an electron

5. Electronegativity
 Electronegativity is…
 how good an atom is at stealing electrons

6. Ionization Energy/Electronegativity
 The trend:
1. IE/E increases across a period (LR)
2. IE/E decreases down a group (Top  Bottom)
Increases
Decreases

7. Example #1
Which has higher amount of ionization energy,
oxygen (O) or carbon (C)?
 Step #1: Find the elements

8. Example
Which has higher amount of ionization energy,
oxygen (O) or carbon (C)?
 Step #2: Look at the keywords
Which has a higher amount of ionization energy,
oxygen (O) or carbon (C)?

9. Example
Which has higher amount of ionization energy,
oxygen (O) or carbon (C)?
 Step #3: Identify which is closest to He

10. Example
Which is less electronegative,
Beryllium (Be) or potassium (K)?
 Step #1: Find the elements

11. Example
Which is less electronegative,
Beryllium (Be) or potassium (K)?
 Step #2: Look at the keyword
Which is less electronegative,
Beryllium (Be) or potassium (K)?

12. Example
Which is less electronegative,
Beryllium (Be) or potassium (K)?
 Step #3: Identify which is closest to Fr

13. Practice Questions
 Review Worksheet #2
 Use the 3-step method!

14. Ionization Energy/Electronegativity
 The trend:
1. IE/E increases across a period (LR)
2. IE/E decreases down a group (Top  Bottom)
Increases
Decreases

15. Atomic Radius
 The trend:
1. Atomic radius decreases across a period (LR)
2. Atomic radius increases down a group (Top  Bottom)
Decreases
Increases

16. Exit Slip
1. Which of the following atoms has the largest
atomic radius?
a. oxygen (O)
b. phosphorus (P)
c. sulfur (S)
d. chlorine (Cl)

17. Exit Slip
2. In general, how does ionization energy vary
throughout the periodic table?
a. it decreases across a period from left to right, and
decreases down a group from top to bottom
b. it increases across a period from left to right, and
increases down a group from top to bottom
c. it increases across a period from left to right, and
decreases down a group from top to bottom
d. It decreases across a period from left to right, and
increases down a group from top to bottom

18. Exit Slip
3. Which of the following atoms has the smallest first
ionization energy?
a. lithium (Li)
b. beryllium (Be)
c. sodium (Na)
d. potassium (K)

19. Exit Slip
4. Electronegativity is the
a. energy it takes to remove an electron from an atom.
b. number of protons and neutrons in an atom.
c. measure of how good an atom is at stealing
electrons.
d. distance from the nucleus to the valence ring.

20. Exit Slip
5. Which of the following correctly lists the elements
in order of increasing electronegativity (least to
most)?
a. O < P < Al < Na
b. Na < Al < P < O
c. P < O < Na < Al
d. Al < P < O < Na

21. Homework
 Finish Review Worksheet #2
 Make a mind map – double points!
 In center oval: “periodic trends”
 In 3 ovals around:
 “atomic radius”
 “electronegativity”
 “ionization energy”
 In 3 boxes for each:
 definition of term
 trend
 picture