CHEM219 – Organic Chemistry Module 3 | Portage Learning | Academic Year
2025/2026 – Complete Exam Collection with Study Notes and Practice Questions
Stereochemistry - (
Answer-the study of the three-dimensional structure of molecules
Stereoisomers - (
Answer-Compounds with the same structural formula and connectivity but with a different 3D
arrangement of the atoms in space.
Enantiomers - (
Answer-Stereoisomers that that are non-superimposable mirror images. Enantiomers have the same
connectivity but different orientations (twist) of the four atoms or groups in 3D space.
The two different forms of the chiral molecule (the "left-handed" form or a "right-handed" forms)
How do the differences caused by steroisomers differ than the differences caused by constitutional
isomers. - (
Answer-While the structural differences between stereoisomers are more subtle than those between
constitutional isomers, stereoisomerism is often responsible for significant differences in the
chemical and physical properties of organic compounds, including the biochemical behavior of many
compounds such as drug molecules, amino acids, carbohydrates, and nucleic acids. Several of the human
senses, especially smell, are greatly affected by stereoisomerism in organic compounds.
cis-stereoisomers - (
Answer-have the substituents on the same side/face of the ring or double bond
trans-stereoisomers - (
Answer-have the substituents on opposite sides/faces of the ring or double bond
Chirality - (
Answer-the concept of "handedness" in an object.
Consider the difference between a pair of socks and a pair of gloves. A sock can be worn
(interchangeably) on either the left or right foot, but the same is not true for the gloves. A left-handed
,glove cannot be worn on the right hand and vice-versa. The gloves possess the property of
"handedness" (chirality)
,Observation will reveal that chiral objects are typically not symmetrical (asymmetric), while achiral
objects typically exhibit multiple planes of symmetry within the object itself.
chiral - (
Answer-a molecule that is not superimposable on its mirror image (possesses the property of
handedness)
achiral - (
Answer-A molecule that is superimposable on its mirror image (does not possess the property of
handedness)
What test can be applied to determine if an object is chiral or achiral? - (
Answer-A simple test involves comparing the object and its mirror image for superimposability.
Superimposability - (
Answer-The ability to align (overlap) two objects so that every unique part of each is in direct alignment
with the same unique part on the other.
What does it mean when a molecule is a chiral molecule? - (
Answer-An organic compound that can exist as two different forms ("left-handed" form or a "right-
handed" form)
Is lactic acid structure chiral or achiral? - (
Answer-Attempting to superimpose lactic acid and its mirror
image reveals that the two forms cannot be superimposed, and thus, the molecule is chiral, and it exists
as two separate forms known as enantiomers (Figure 3.4). No matter how one of the structures is
rotated, it is impossible to get all of the atoms/groups in one to align with the same atoms/groups in the
mirror image structure.
Is the molecule 2-chloropropane chiral or achiral? - (
Answer-When the 3D structure of this molecule is drawn, a tetrahedral geometry is observed around the
central carbon, similar to that of lactic acid. At first glance, it may not be clear that the molecule is
achiral. It is only through the application of the superimposability test that the molecule reveals its
achiral nature.
, The absence of a stereocenter is the reason why molecules like 2-chloropropane are achiral. An analysis
of the 3D structure of 2-chloropropane reveals a tetrahedral geometry around the central carbon but
2025/2026 – Complete Exam Collection with Study Notes and Practice Questions
Stereochemistry - (
Answer-the study of the three-dimensional structure of molecules
Stereoisomers - (
Answer-Compounds with the same structural formula and connectivity but with a different 3D
arrangement of the atoms in space.
Enantiomers - (
Answer-Stereoisomers that that are non-superimposable mirror images. Enantiomers have the same
connectivity but different orientations (twist) of the four atoms or groups in 3D space.
The two different forms of the chiral molecule (the "left-handed" form or a "right-handed" forms)
How do the differences caused by steroisomers differ than the differences caused by constitutional
isomers. - (
Answer-While the structural differences between stereoisomers are more subtle than those between
constitutional isomers, stereoisomerism is often responsible for significant differences in the
chemical and physical properties of organic compounds, including the biochemical behavior of many
compounds such as drug molecules, amino acids, carbohydrates, and nucleic acids. Several of the human
senses, especially smell, are greatly affected by stereoisomerism in organic compounds.
cis-stereoisomers - (
Answer-have the substituents on the same side/face of the ring or double bond
trans-stereoisomers - (
Answer-have the substituents on opposite sides/faces of the ring or double bond
Chirality - (
Answer-the concept of "handedness" in an object.
Consider the difference between a pair of socks and a pair of gloves. A sock can be worn
(interchangeably) on either the left or right foot, but the same is not true for the gloves. A left-handed
,glove cannot be worn on the right hand and vice-versa. The gloves possess the property of
"handedness" (chirality)
,Observation will reveal that chiral objects are typically not symmetrical (asymmetric), while achiral
objects typically exhibit multiple planes of symmetry within the object itself.
chiral - (
Answer-a molecule that is not superimposable on its mirror image (possesses the property of
handedness)
achiral - (
Answer-A molecule that is superimposable on its mirror image (does not possess the property of
handedness)
What test can be applied to determine if an object is chiral or achiral? - (
Answer-A simple test involves comparing the object and its mirror image for superimposability.
Superimposability - (
Answer-The ability to align (overlap) two objects so that every unique part of each is in direct alignment
with the same unique part on the other.
What does it mean when a molecule is a chiral molecule? - (
Answer-An organic compound that can exist as two different forms ("left-handed" form or a "right-
handed" form)
Is lactic acid structure chiral or achiral? - (
Answer-Attempting to superimpose lactic acid and its mirror
image reveals that the two forms cannot be superimposed, and thus, the molecule is chiral, and it exists
as two separate forms known as enantiomers (Figure 3.4). No matter how one of the structures is
rotated, it is impossible to get all of the atoms/groups in one to align with the same atoms/groups in the
mirror image structure.
Is the molecule 2-chloropropane chiral or achiral? - (
Answer-When the 3D structure of this molecule is drawn, a tetrahedral geometry is observed around the
central carbon, similar to that of lactic acid. At first glance, it may not be clear that the molecule is
achiral. It is only through the application of the superimposability test that the molecule reveals its
achiral nature.
, The absence of a stereocenter is the reason why molecules like 2-chloropropane are achiral. An analysis
of the 3D structure of 2-chloropropane reveals a tetrahedral geometry around the central carbon but
