CHEM 3: Quiz 3 Name:____________________________________________________________________ Points: _____ / 50

Please read each question carefully. Show your work, and partial credit will be awarded where possible.

1. (1 point) How many valence electrons does a neutral Iodine atom have?_________________

2. (1 points) How many electrons would be included in the Lewis dot structure of sulfate, SO42-?________________

3. (1 points) How many electrons would be included in the Lewis dot structure of PH4

+?_________________

4. (1 points) Select the Lewis dot structure below that is reasonable and valid.

A. B. C. D.

E. NONE of the structures above are reasonable or valid.

5. (2 points) Draw the Lewis dot structure for the polyatomic ANION selenite, SeO32-.

6. (2 points) Draw the Lewis dot structure for the molecule: CH3-SO-CH3.

Hint: Sulfur is the central atom with a C—S—C sequence.

CHEM 3: Quiz 3

7. (1 point) Circle any statements below that are CORRECT regarding VSEPR Theory.

A. VSEPR theory predicts molecular shapes by considering how electron-electron repulsions maximize the distance between adjacent groups.

B. Bonding regions are repelled from one another and exclusively determine the electron geometry about a central atom. C. The electron geometry and molecular geometry will be equivalent when there are lone pairs coming off the central atom. D. The ideal bond angles in a tetrahedron are 120o. E. None of the statements above are CORRECT.

8. Below is the VALID Lewis dot structure for ozone (O3). A. (1 point) What is the electron geometry at the central oxygen atom?

B. (1 point) What is the molecular geometry at the central oxygen atom?

9. Below is the VALID Lewis dot structure for the polyatomic anion, arsenite (AsO2-).

A. (1 point) What is the electron geometry at the central arsenic atom?

B. (1 point) What is the molecular geometry at the central arsenic atom? 10. (1 point) Below is the VALID Lewis dot structure for silane (SiH4). What is the approximate H—Si—H bond angle?

11. (1 point) Below is the VALID Lewis dot structure for nitrite (NO2

-). What is the approximate O—N—O bond angle?

12. (2 points) Roxarsone is a compound that has been widely used agriculturally as a chicken-feed additive, despite containing Arsenic. Given the VALID lewis dot structure for Roxarsone (to the right), fill in each blank on the diagram.

CHEM 3: Quiz 3

13. (3 points) In the space provided below, categorize each of the following bonds according to their polarity. Within each category (non-polar covalent, polar covalent, ionic), ARRANGE THE BONDS WITH INCREASING POLARITY from LEFT TO RIGHT.

Mg—F C—O C—H C—C Cs—F O—H

Non-polar Covalent Bonds Polar Covalent Bonds Ionic Bonds

INCREASING POLARITY

14. (1 points) Draw the partial charges and dipole moment for the polar bond below.

P—Cl 10. (4 points) Based on the valid Lewis dot structures below, circle all of the POLAR molecules.

Hint: The molecules may NOT be written with the proper three-dimensional shape. Be sure to consider the actual molecular shapes before deciding upon the molecular polarities.

EXTRA CREDIT: 2 points, no partial credit awarded

CHEM 3: Quiz 3

A. Draw a reasonable Lewis dot structure for a molecule that meets the two criteria below.

Empirical formula = CHF

NONPOLAR overall B. Based on your Lewis dot structure, why is the molecule above NONPOLAR?