CHM-151 EXAM 3

Periodic Trends

100

What is the most electronegative element?

Fluorine

200

Please place the following elements in order of increasing atomic radius:

K, Fr, Br, F

Smallest -------- Largest 

F, Br, K, Fr

300

Which bond would be the most polar?

H-H                     H-BR

H-F                      H-I

H-O                     H-At

H-F

400

Please write the following ions in order of increasing size

Ca²⁺     P^3-     K⁺     Cl^-     S^2-

Smallest ----------------- Largest

Ca²⁺, K⁺, Cl^-, S^2-, P^3-

500

Which element would have the highest difference between the second and third ionization energies?

Cl          O

N          Al

Mg        Na

Mg

Lewis Structure 1

100

Please draw the lewis structure for Nitrogen Trifluoride.

NF₃

200

Please draw the lewis structure for Phosphorus Pentafluoride. 

Is it polar or nonpolar?

PCl₅

Nonpolar

300

Please draw the lewis structure for OCCl₂

OCCl₂

400

Please draw the lewis structure for CO₂. Include two additional resonance structures. Which is the most stable?

CO₂

500

Please draw the lewis structure for CH₃OH

Double points if you can name it!

methanol

Geometry

100

Please draw the lewis structure for CCl₄.

What is the molecular geometry and bond angle(s)?

CCl₄

tetrahedral

109.5

200

Please draw the lewis structure for H₂O.

What is the electron and molecular geometry?

What are the bond angles?

H₂O

electron: tetrahedral

molecular: bent

104.5

300

Please draw the lewis structure for SF₄.

What is the electron and molecular geometry?

Double points if you tell me the bond angles.

SF₄

electron: trigonal bipyramidal 

molecular: seesaw

102, 173

400

Please draw the lewis structure for XeF₄.

What is the electron and molecular geometry?

What are the bond angles?

Is it polar or nonpolar?

XeF₄

electron: octahedral

molecular: square planar

90

nonpolar

500

Please draw the lewis structure for I₃^-.

What is the electron and molecular geometry?

What are the bond angles?

Is it polar or nonpolar?

I₃^-

electron: trigonal bipyramidal

molecular: linear

180

nonpolar

Lewis Structure 2

100

Please draw the lewis structure for PCl₃.

Is it polar or nonpolar?

PCl₃

polar

200

Please draw the lewis structure for BrCl₃.

Is it polar or nonpolar?

BrCl₃

polar

300

Please draw the lewis structure for SCN^-.

Please include two additional resonance structures and identify which is the most stable.

SCN^-

400

Please draw the lewis structure for H₂CN₂ and determine the formal charges.

H₂CN₂

500

Please draw the lewis structure for C₅H₁₂​

Double points if you can name it and draw it like an organic chemist.

​​​

C₅H₁₂

Pentane

Bonds and Hybridization

100

Please draw the lewis structure for CH₄.

What is the hybridization of the central carbon?

CH₄

sp³

200

Please draw the lewis structure for H₂CO

What is the hybridization of the central carbon?

H₂CO

sp²

300

Please draw the lewis structure for BrF₄⁺

What is the hybridization of the central atom?

BrF₄⁺

sp³d

400

For acetylcholine:

How many sigma and pi bonds are present?

What is the hybridization of oxygens? (hint: they're not the same)

Acetylcholine:

Sigma: 21

Pi: 1

Double bonded oxygen: sp²

Oxygen with two bonds: sp³

500

For caffeine:

How many sigma and pi bonds are present?

Caffeine:

sigma: 25

pi: 4