Lewis Diagrams (College Board AP® Chemistry)

Exam Questions

13 mins10 questions
1a1 mark

 

Nonmetal

C

N

O

Ne

Si

P

S

Ar

Formula of

Compound

 

CF4

 

NF3

 

OF2

No compound

 

SiF4

 

PF3

 

SF2

No compound

 

Some binary compounds that form between fluorine and various nonmetals are listed in the table above. A student examines the data in the table and poses the following hypothesis: the number of F atoms that will bond to a nonmetal is always equal to 8 minus the number of valence electrons in the nonmetal atom.

Based on the student’s hypothesis, what should be the formula of the compound that forms between chlorine and fluorine?

1b1 mark

In an attempt to verify the hypothesis, the student researches the fluoride compounds of the other halogens and finds the formula ClF3 . In the box below, draw a complete Lewis electron-dot diagram for a molecule of ClF3 .

empty box
1c1 mark

Two possible geometric shapes for the ClF3 molecule are trigonal planar and T-shaped. The student does some research and learns that the molecule has a dipole moment. Which of the two shapes is consistent with the fact that the ClF3 molecule has a dipole moment? Justify your answer in terms of bond polarity and molecular structure.

1d1 mark

In an attempt to resolve the existence of the ClF3 molecule with the hypothesis stated above, the student researches the compounds that form between halogens and fluorine, and assembles the following list.

Halogen

Formula(s)

F

F2

Cl

 

Br

BrF, BrF3 , BrF5

I

IF, IF3 , IF5 , IF7

 Based on concepts of atomic structure and periodicity, propose a modification to the student’s previous hypothesis to account for the compounds that form between halogens and fluorine.

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