Launch: 9/24   Grab your binder and immediately take a seat

  Place Textbook HW on desk

5. Which of the following atoms has the largest atomic radius? a. oxygen (O)

b. phosphorus (P) c. sulfur (S) d. chlorine (Cl)

What is the trend for ionization energy?

Mr. Heffner 9/24/09

Review: Atomic Radius In

crea

ses

Decreases

IV. Ionization Energy A.  What is ionization energy?

1.  The energy it takes to remove an electron from an atom

2.  Atoms can have multiple ionization energies i.  First ionization energy – the energy it takes to remove the

first electron

ii.  Second ionization energy – the energy it takes to remove the second electron

iii. Third ionization energy – the energy it takes to remove the third electron

IV. Ionization Energy B.  What is the trend for first ionization energy?

1.  Ionization energy increases across a period (LR) i.  As the number of protons increases, atomic radius

decreases

ii.  It is harder to take an electron off a small atom, so ionization energy increases

Chihuahua Story   I am a dog walker and everyday I walk 8

  The stronger I am, the closer I can pull them towards me

  The closer they are to me, the harder they are to steal!

IV. Ionization Energy B.  What is the trend for first ionization energy?

2.  Ionization energy decreases down a group (TopBottom)

i.  As the number of electrons increases, atomic radius increases

ii.  It is easier to take an electrons off a large atom, so ionization energy decreases

Chihuahua Story   I am a dog walker and now I have 9

  I can’t fit any more around me, need a longer leash

  It is easier to steal one when it is farther away!

IV. Ionization Energy D

ecre

ases

Increases

IV. Ionization Energy A.  What is the trend for second & third ionization

energy? 1.  The trend is the same as first ionization energy

2.  However, the amount of energy is always larger than first

i.  After one electron is removed, the protons pull the remaining electrons closer to the nucleus making the atom smaller

ii.  It is harder to take an electron off a small atom, so second ionization energy is larger than first

Practice Questions 1.  What is ionization energy?

2.  Describe the trend for ionization energy. How does it compare to atomic radius?

3.  Which has a larger ionization energy, P or S; F or Cl; Li or Cs; Pt or Ni; Fr or F; Se or O?

4.  Which element in group 2 has the largest ionization energy? The smallest?

5.  Magnesium has a first ionization energy of 737.7 kJ/mol and second ionization energy of 1450.7 kJ/mol. Use what you know to explain this phenomenon in at least two complete sentences.

Homework   Textbook Problems:

  Pg. 141 Section Review: #1, 5, 11, 12, 13

  Finish Practice Problems

  Start reviewing for Monday’s Unit #2 Exam!

  lpschem.wordpress.com

Exit Slip 1. Ionization energy is the

a. number of stable ions formed by an atom. b. number of protons and neutrons in an atom.

c. energy it takes to remove an electron from an atom. d. distance from the nucleus to the valence ring.

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

Exit Slip 3. Which of the following correctly describes the

relationship between first and second ionization energy? a. First ionization energy is always larger than second

b. Second ionization energy is always larger than first c. First ionization energy describes positively-charged

ions, while second ionization energy describes negatively-charge ions

d. First ionization energy describes negatively-charged ions, while second ionization energy describes positively-charge ions

Exit Slip 4. Which of the following atoms has the smallest first

ionization energy? a. lithium (Li) b. beryllium (Be) c. sodium (Na)

d. magnesium (Mg)

5. The chart above shows the relationship between the first ionization energy and the increase in atomic number. The letter on the chart that represents the noble gases is:

a. W

b. X c. Y d. Z