EXAM 2 (Chap. 5 - 7) Study Guide

Question 1

PF₃

_{How many valence electrons are in this molecule?}

Answer 1

26 valence electrons.

Phosphorous (P) = 5 valence electrons, or group 5A

Fluorine (F) = 7 valence electrons, or group 7A

**5 + (3) 7 = 26 **

Question 2

PF₃

Draw the Lewis Dot Structure of this molecule.

Answer 2

N: 8 + (3) 8 = 8 + 24 = 32 electrons that are needed

A: 5 + (3) 7 = 5 + 21 = 26 electrons that are already there

S: 32 – 26 = 6 shared electrons (3 bonds)

U: 26 – 6 = 20 unshared electrons (10 lone pairs)

Question 3

PF₃

What is the molecular geometry of this molecule?

Answer 3

Pyramid (polar).

Question 4

A saturated solution will form when 357 grams of sodium chloride is dissolved in one liter of water. How many grams of sodium chloride are necessary to form 2.5 liters of saturated solution?

Answer 4

357 grams of NaCl in 1 L of water.

______ grams in 2.5 L?

Question 5

A saturated solution will form when 1220 grams of silver nitrate is dissolved in one liter of water. How many grams of silver nitrate are necessary to form 0.500 liters of saturated solution?

Answer 5

1220 grams of silver nitrate in 1 Liter of water.

____ grams in 0.500 Liters of water?