Chem-To-Go Lesson 12Unit 3

IONIZATION ENERGY &

ELECTRONEGATIVITY

1ST IONIZATION ENERGY

Definition: the energy required to remove a first electron from an atom

1ST IONIZATION ENERGY

1ST IONIZATION ENERGY

Period trend: [row pattern]; ionization energy INCREASES from left to right across a row Group trend: [column pattern]; ionization energy INCREASES from bottom to top of a column

WHY?•The energy needed to remove an electron increases as the nucleus becomes more strongly positive and the electrons are drawn in closer to it.

• The energy needed to remove an electron increases as the valence electrons are closer to the nucleus. The shielding effect makes removing electrons easier from higher energy levels.

PERIOD TREND

GR

OU

P T

REN

D

1ST IONIZATION ENERGY

SHIELDING EFFECT OF CORE ELECTRONS•The energy needed to remove an electron increases as the valence electrons are closer to the nucleus. The shielding effect makes removing electrons easier from higher energy levels.

1ST IONIZATION ENERGYMemory

Tool

SAMPLE MULTIPLE CHOICE:

1. Which of the following atoms will has the smallest ionization energy?

a. Tin b. Strontium c. Selenium d. Arsenic

• Use a periodic table!• Find all of the elements.• Apply the trend.

1ST IONIZATION ENERGYMemory

Tool

SAMPLE MULTIPLE CHOICE:

2. Which of the following atoms has a larger ionization energy than calcium?

a.Aluminum b. Copper c. Potassium d. None

• Use a periodic table!• Find all of the elements.• Apply the trend.

ELECTRONEGATIVITY

Definition: the ability of an atom in a chemical bond to draw the bonding electrons closer to itself

ELECTRONEGATIVITY

Notice that the noble gases are NOT in the image. Since they don’t form bonds, they have no

electronegativity values.

ELECTRONEGATIVITY

Period trend: [row pattern]; electronegativity INCREASES from left to right across a row Group trend: [column pattern]; electronegativity INCREASES from bottom to top of a column

WHY?•The larger and more positive nuclei on the right side of the table are more likely to attract the bonding electrons

• An unshielded nucleus is better at attracting bonding electrons. Fewer energy levels means more electronegativity.

PERIOD TREND

GR

OU

P T

REN

D

ELECTRONEGATIVITYMemory

Tool

SAMPLE MULTIPLE CHOICE:

1. Which of the following atoms will has the highest electronegativity?

a. Tin b. Chlorine c. Neon d. Arsenic

• Use a periodic table!• Find all of the elements.• Apply the trend.

ELECTRONEGATIVITYMemory

Tool

SAMPLE MULTIPLE CHOICE:

2. Which of the following atoms will has a higher electronegativity than P?

a.Oxygen b. Fluorine c. Helium d. None

• Use a periodic table!• Find all of the elements.• Apply the trend.