Chem Ch 15. The Three-Dimensional Shape of Molecules

What is a chirality center in a molecule? Any tetrahedral carbon atom A carbon atom with trigonal planar geometry A carbon atom that is bonded to four other carbon atoms A carbon atom that is bonded to four different groups

A carbon atom that is bonded to four different groups

Which statement correctly describes a racemic mixture? An equal mixture of two cis, trans isomers A mixture of enantiomers of two different chiral compounds A mixture of two constitutional isomers An equal mixture of two enantiomers

An equal mixture of two enantiomers

How is it possible that the two enantiomers of a chiral drug can have different biological activities? One enantiomer of a chiral drug is typically more soluble than the other in biological fluids, and is thus better able to reach the target. One enantiomer of a chiral drug is often missing the necessary functional groups to interact with a biological target molecule. Biological targets are also chiral, and will therefore "fit" differently with the two enantiomers of a chiral drug.

Biological targets are also chiral, and will therefore "fit" differently with the two enantiomers of a chiral drug.

Which of the following is NOT a step in determining whether a given molecule is chiral? Determine whether all atoms/bonds in the structures can be aligned. Draw the molecule in three dimensions. Draw the mirror image of the molecule in three dimensions. Rotate any molecule as necessary. Break, realign, and reform any bonds as necessary.

Break, realign, and reform any bonds as necessary.

Which of the following statements correctly describes stereoisomers? Compounds that have the same formula and differ only in the three-dimensional orientation of atoms Compounds that contain the same functional group(s) but differ in their chemical formulas Compounds that have the same formula and differ in the order in which atoms are connected

Compounds that have the same formula and differ only in the three-dimensional orientation of atoms

Which of the following statements correctly describes constitutional isomers? Compounds with the same formula that differ in the orientation of atoms in space Compounds with the same formula that differ in the connectivity of atoms Compounds with the same functional group but different formulas

Compounds with the same formula that differ in the connectivity of atoms

Which of the following statements correctly describes isomers? Different naturally occurring forms of the same element Atoms of the same element that have different masses Different compounds that have the same molecular formula Different compounds that have the same functional group

Different compounds that have the same molecular formula

Which of the following are steps in determining whether a given molecule is chiral? Draw the molecule in three dimensions. Draw the mirror image of the molecule. Try to align the mirror image with the original in three dimensions. If necessary, rearrange any atoms that are bonded to a central atom. Draw the molecule as a two-dimensional Lewis structure.

Draw the molecule in three dimensions. Draw the mirror image of the molecule. Try to align the mirror image with the original in three dimensions.

Which of the following are examples of chirality in nature? A corkscrew A water molecule Many biological molecules Helical seashells

Helical seashells Many biological molecules

Dihydroxyphenylalanine (dopa) is a natural product that can be isolated from plants. Match each enantiomer of dopa with its biological activity. L-dopa D-dopa - active against Parkinson's disease - causes neutropenia

L-dopa - active against Parkinson's disease D-dopa - causes neutropenia

Many drugs are chiral molecules, which means that two enantiomers of a given drug molecule are possible. Which general statement best describes the biological activities of two enantiomers of a given drug? The enantiomers may have similar activities or different activities. The two enantiomers will always have the same biological activity. The two enantiomers will always have clearly different biological activities.

The enantiomers may have similar activities or different activities.

True or false: Any molecule with one chirality center is chiral.

True

If an object CAN be superimposed on its mirror image, it is said to be _____

achiral

The two enantiomers of a chiral compound can have different _____ activities. For example, one enantiomer of thalidomide has sedative properties, while the other enantiomer is a teratogen.

biological

A chiral object ______. does not have a mirror image cannot be superimposed on its mirror image is any object with a tetrahedral geometry

cannot be superimposed on its mirror image

A tetrahedral carbon atom that is bonded to four different atoms/groups is known as a _____ center

chirality

The helical shells of snails and the left-handed winding of a vine are examples of ______ in nature. isomerism chirality functional groups mirror images

chirality

Compounds that have the same molecular formula but differ in the way in which the atoms are connected are known as _____ isomers

constitutional or structural

Different compounds that have the same molecular formula are known as _____

isomers

Any molecule is chiral if it contains ______ chirality center(s). two or more no one

one

A 50:50 mixture of the two enantiomers of a chiral compound is known as a _____ mixture

racemic

Compounds that differ only in the three-dimensional arrangement of their atoms are called ______ isomers. stereo constitutional structural rotational

stereo

Biological molecules such as cell receptor proteins are chiral molecules. As a result, the two enantiomers of a chiral drug ______. will often have different biological activities will interact with the target in the same way

will often have different biological activities