A secondary amine is an amine (nitrogen atom) that is attached to two carbon-containing groups (alkyl groups or aryl groups). The nitrogen in ephedrine is attached to two alkyl groups, making it a secondary amine.

Primary amines are generally written as . Secondary amines are generally written as . A tertiary amine will be bound to three different R-groups. Quaternary amines require a positive charge on the nitrogen atom to accommodate a fourth R-group.

A chiral center is defined as a tetrahedral atom with four unique substituents. In the molecule above there exists only one carbon that has four different substituents, which is carbon #4 (counting from the right). Carbon #4 has -chloro and -hydroxy groups, as well as two different longer alkyl chains. No other atom has four unique substituents.

An enantiomer is defined as a stereoisomer that is a mirror image of another. In other words, if a molecule was placed in front of a mirror, its mirror image would be the enantiomer. Questions such as these require a bit of visualization, but should be easy points. In addition, if you see the answer choice quickly and are confident in your decision, move onto the next question without spending time on the other choices, as mental geometry and visualization may take more time than anticipated.

A secondary amine is an amine (nitrogen atom) that is attached to two carbon-containing groups (alkyl groups or aryl groups). The nitrogen in ephedrine is attached to two alkyl groups, making it a secondary amine.

Primary amines are generally written as . Secondary amines are generally written as . A tertiary amine will be bound to three different R-groups. Quaternary amines require a positive charge on the nitrogen atom to accommodate a fourth R-group.

A chiral center is defined as a tetrahedral atom with four unique substituents. In the molecule above there exists only one carbon that has four different substituents, which is carbon #4 (counting from the right). Carbon #4 has -chloro and -hydroxy groups, as well as two different longer alkyl chains. No other atom has four unique substituents.

An enantiomer is defined as a stereoisomer that is a mirror image of another. In other words, if a molecule was placed in front of a mirror, its mirror image would be the enantiomer. Questions such as these require a bit of visualization, but should be easy points. In addition, if you see the answer choice quickly and are confident in your decision, move onto the next question without spending time on the other choices, as mental geometry and visualization may take more time than anticipated.

Meso compounds are compounds that contain two or more chiral carbons, however, the chiral carbons offset each other resulting in an achiral compound. You can recognize meso compounds because they will have a plane of symmetry.

By drawing the Lewis structures of these molecules, we can determine the bond angles between the atoms. The following molecular geometries contain bond angles of : octahedral, trigonal bipyramidal, and square planar.

has a tetrahedral geometry, which means that there are only bond angles of .

will be square planar. will be octahedral. will be trigonal bipyramidal.

By drawing the Lewis structures of these molecules, we can determine the bond angles between the atoms. The following molecular geometries contain bond angles of : octahedral, trigonal bipyramidal, and square planar.

has a tetrahedral geometry, which means that there are only bond angles of .

will be square planar. will be octahedral. will be trigonal bipyramidal.

Meso compounds are compounds that contain two or more chiral carbons, however, the chiral carbons offset each other resulting in an achiral compound. You can recognize meso compounds because they will have a plane of symmetry.