CHEM 219 EXAM 1 ALL - SOLUTION Question :On a piece of scratch paper,...

• | Page

CHEM 219 EXAM 1 ALL

QUESTIONS WITH COMPLETE

SOLUTION

Question :On a piece of scratch paper, write out the Lewis

Dot Diagram for each of the indicated elements and

determine the following for each:

a) The number of Lone Pairs the atom possesses in its

valence shell.b) The number of Unpaired Electrons the atom possesses in its valence shell.c) The number of bonds the atom will form.

Oxygen Carbon Hydrogen Nitrogen

Correct answer:Oxygen - a) 2 b) 2 c) 2

Carbon - a) 0 b) 4 c) 4 Hydrogen- a) 0 b) 1 c) 1 Nitrogen - a) 1 b) 3 c) 3

• | Page

Question :Classify the bonding between the given pairs of

atoms as ionic, covalent, or polar covalent. Use the table of electronegativities shown below to help with the classification.

• Br and Br
• K and Cl
• P and Cl
• C and O
• Na and Br

Correct answer:a. Br-Br: Electronegativity difference () =

• = COVALENT (or pure covalent)

b. K-Cl: () = 2.2 = IONIC

c. P-Cl: ()= 0.9 = POLAR COVALENT

d. C-O: ()= 1.0 = POLAR COVALENT

e. Na-Br: () = 1.8 = POLAR COVALENT

Question :Define the term constitutional isomer.

Correct answer:Two (or more) different chemical

compounds with the same molecular formula but different

• | Page

connectivity between the atoms in their structural formulae.

Question :Explain (using specific evidence) what makes

the following two compounds constitutional isomers of

one another:

Correct answer:Both compounds have a MF of C3H6O -

same MF.Compound "a" has a 3-carbon chain with a C=O in the middle. No H atom connected to C of C=O.Compound "b" has a 3-carbon chain with a C=O at the end. There is an H attached to the C of the C=O.

Question :What is the relationship between the

compounds shown? Are they the same compound, constitutional isomers, or two different compounds that are not related to one another? Explain.

Correct answer:Different compounds that are not related.

They have different MF - (a) C3H8O, (b) C3H6O.

• | Page

Question :Identify each of the following carbon skeletons

as linear (continuous), branched, or cyclic.

a) Branched

b) Linear (continuous)

c) Cyclic

Correct answer:a) Branched

b) Linear (continuous)

c) Cyclic

Question :On a piece of scratch paper, write out structural

formulae for all of the constitutional isomers possible for the MF C3H6F2. How many isomers are possible for this formula?

Correct answer:4

Question :Characterize each of the following structural

formula representations as either a dash, condensed,

super-condensed, or bond-line formula:

a) Super-Condensed

b) Condensed