Launch: 9/25   Grab your binder and immediately take a seat

  Place Textbook HW on desk

5. The chart below 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

What is the trend for electronegativity?

Mr. Heffner 9/25/09

Review: Atomic Radius In

crea

ses

Decreases

IV. Ionization Energy D

ecre

ases

Increases

V. Electronegativity A.  What is electronegativity?

1.  The ability of an atom to attract electrons toward itself in a chemical bond

H

H

O

V. Electronegativity B.  What is the trend for electronegativity?

1.  Electronegativity increases across a period (LR) i.  As the number of protons increases, the nucleus gets

stronger and pulls all nearby electrons towards it

V. Electronegativity B.  What is the trend for electronegativity?

2.  Electronegativity decreases down a group (TopBottom) i.  As the number of electrons increases, more rings are added

ii.  The inner rings shield other electrons from the attractive forces of the nucleus

V. Electronegativity D

ecre

ases

Increases

Practice Questions   See Periodic Trends Worksheet

Homework   Study for Monday’s Unit #2 Exam!

  Look over Quiz #3   Look over Exit Slips

  lpschem.wordpress.com

Exit Slip 1. Electronegativity is the

a. energy it takes to remove an electron from an atom. b. number of protons and neutrons in an atom.

c. ability of an atom to attract electrons toward itself in a chemical bond

d. distance from the nucleus to the valence ring.

Exit Slip 2. In general, how does electronegativity 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. Why does electronegativity decrease down a group?

a. Because atomic radius decreases b. Because the nucleus is shielded by the inner rings

c. Because the outer electrons are more strongly attracted by the nucleus

d. Because the trend for electronegativity increases down a group

Exit Slip 4. Which of the following atoms is more

electronegative than S? a. oxygen (O) b. phosphorus (P) c. selenium (Se)

d. magnesium (Mg)

Exit Slip 5. Which of the following atoms is the most

electronegative? a. sodium (Na) b. phosphorus (P) c. selenium (Se)

d. magnesium (Mg)