CHEM 219 Module 1 questions and answers
2025-2026 update
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 - ✔✔ANS 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
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.
a. Br and Br
b. K and Cl
c. P and Cl
d. C and O
e. Na and Br - ✔✔ANS a. Br-Br: Electronegativity difference () = 0 = 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
, Define the term constitutional isomer. - ✔✔ANS Two (or more) different chemical compounds with the
same molecular formula but different connectivity between the atoms in their structural formulae.
Explain (using specific evidence) what makes the following two compounds constitutional isomers of
one another: - ✔✔ANS 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.
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. - ✔✔ANS Different
compounds that are not related. They have different MF - (a) C3H8O, (b) C3H6O.
Identify each of the following carbon skeletons as linear (continuous), branched, or cyclic. - ✔✔ANS a)
Branched
b) Linear (continuous)
c) Cyclic
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? - ✔✔ANS 4
Characterize each of the following structural formula representations as either a dash, condensed,
super-condensed, or bond-line formula: - ✔✔ANS a) Super-Condensed
b) Condensed
c) Bond-line
d) Dash
Write the molecular formula for each of the compounds whose bond-line formulae are given below. -
✔✔ANS a) C5H10
b) C3H8O
c) C4H10O
2025-2026 update
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 - ✔✔ANS 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
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.
a. Br and Br
b. K and Cl
c. P and Cl
d. C and O
e. Na and Br - ✔✔ANS a. Br-Br: Electronegativity difference () = 0 = 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
, Define the term constitutional isomer. - ✔✔ANS Two (or more) different chemical compounds with the
same molecular formula but different connectivity between the atoms in their structural formulae.
Explain (using specific evidence) what makes the following two compounds constitutional isomers of
one another: - ✔✔ANS 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.
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. - ✔✔ANS Different
compounds that are not related. They have different MF - (a) C3H8O, (b) C3H6O.
Identify each of the following carbon skeletons as linear (continuous), branched, or cyclic. - ✔✔ANS a)
Branched
b) Linear (continuous)
c) Cyclic
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? - ✔✔ANS 4
Characterize each of the following structural formula representations as either a dash, condensed,
super-condensed, or bond-line formula: - ✔✔ANS a) Super-Condensed
b) Condensed
c) Bond-line
d) Dash
Write the molecular formula for each of the compounds whose bond-line formulae are given below. -
✔✔ANS a) C5H10
b) C3H8O
c) C4H10O
