Chem 200 Exam 3 Review

Lewis Dot Structures

100

How many electron pairs are shared between the carbon atoms in C2H4?

2

200

In carbon disulfide, how many lone pairs of electrons are on each sulfur atom?

2

300

Which of the following molecules contains a double bond?

I2

PCl5

C₂H₂

N2

CH₂O

CH₂O

400

How many resonance structures are possible for NO₃^-?

3

500

What is the correct lewis structure for NOCl?

O = N - Cl

2 lone pairs on O

1 lone pair on N

3 lone pairs on Cl

VSPER

100

What is the molecular structure of thiocyanate anion, SCN-, as predicted by VSPER?

linear

200

What are the angles present in trigonal bipyramidal geometry?

90, 120 180

300

Which one of the following ions and molecules is most likely to be planar?

BrF3

H3O⁺

PCl3

SO4^2-

SF4

BrF3

400

Which one of the following molecules and ions will have a square planar geometry as predicted by VSEPR?

PCl3

BF₄^-

XeF₄

BrF5

H3O⁺

XeF4

500

Predict the smallest actual bond angle in XeO₃^2- using VSEPR.

a. more than 120

b. exactly 120

c. between 109 and 120

d. between 90 and 109

e. less than 90

E

MO Diagrams

100

How do you calculate bond order?

bonding - antibonding / 2

200

Which of the following diatomic molecules are paramagnetic?

C2

N2⁺

F2

Ne2

N2

N2⁺

300

What is the bond order for Ne₂?

0

400

Which of the following diatomic molecules has the greatest number of electrons in anti-bonding molecular orbitals?

CN-

O2^2-

F2+

BN+

N2

O2^2-

500

What is the bond order for BN-?

2.5

Hybridization

100

What is the hybridization of the central atom in water?

sp3

200

What is the hybridization of carbon in ClCN?

sp

300

What is the hybrid orbital for carbon in a carbonate anion, CO₃^2-?

sp2

400

Which one of these is paired incorrectly?

Linear - sp

bent - sp3

square planar - sp3d2

trigonal planar - sp2

t-shaped - sp3

t-shaped - sp3

500

Draw the lewis dot structure for a phosphate ion and calculate the formal charge for each atom?

P = 0

O = -1, -1, -1

O = 0

Concept Qs

100

Which of these elements has the lowest electronegativity?

Li, Al, Cl, Cs, Ca

Cs

200

Which one of the following properties is least characteristic of typical ionic compounds?

high melting point

poor electrical conductor when molten

high boiling point

brittleness

poor electrical conductor when solid

poor electrical conductor when molten

300

Which of these has the most polar bond?

C-O

Si-F

Cl-F

C-F

C-I

Si-F

400

Based on the electronegativity trends in the periodic table, predict which of the following compounds will have the greatest percent ionic character in its bonds:

H2O

LiI

CaO

RbF

HCl

RbF

500

The diameter of a chloride ion is 360 pm, and the diameter of a potassium ion is 280 pm. What is the distance between adjacent chloride and potassium ions in solid potassium chloride?

320 pm