(c) Stereo Chemistry Flashcards

1
Q

What is an isomer?

A

Molecules with the same molecular formula but different structural formulas.

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2
Q

What is a structural isomer?

A

When atoms are bonded together in a different order in each isomer.

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3
Q

When do stereoisomers occur?

A

When the order of the bonding in the atoms is the same but the spatial arrangement ent of the atoms is different each isomer.

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4
Q

How many types of stereoisomers are there?

A

2.

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5
Q

What are the 2 types of stereoisomers?

A

Geometric and optical.

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6
Q

When do geometric isomers occur?

A

When there is restricted rotation around a carbon to carbon double bond, or a carbon to carbon single bond in a cyclical structure.

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7
Q

What must there be in order for geometric isomers to occur?

A

2 different groups attached to each of the carbon atoms that make up the bond with restricted rotation.

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8
Q

How can geometric isomers be labelled?

A

cis or trans.

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9
Q

What is a cis geometric isomer?

A

If the 2 different groups are on the same side.

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10
Q

What is a trans geometric isomer?

A

If the 2 different groups are on different sides.

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11
Q

How can geometric isomers differ?

A

Different physical properties, e.g. melting and boiling points. They can also have different chemical properties.

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12
Q

How do optical isomers occur?

A

In compounds in which 4 different groups are arranged tetrahedrally around a central carbon atom.

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13
Q

If a carbon is attached to 4 different functional groups what is it known as?

A

Chiral carbon.

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14
Q

Are optical isomers symmetric or asymmetric?

A

Asymmetric.

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15
Q

How do optical isomers differ from each other?

A

They are non-superimposable images of each other.

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16
Q

How can optical isomers be described?

A

Enantiomers.

17
Q

What is different between optical isomers?

A

Their effect on polarised light.

18
Q

What is the same about optical isomers?

A

Everything bearing their effect on polarised light.

19
Q

What different chemical properties do optical isomers have?

A

None except when is a chiral environment.

20
Q

What is an example of a chiral environment?

A

Biological systems.

21
Q

How do optical isomers affect polarised light?

A

They rotate polarised light by the same amount, but in opposite directions.

22
Q

What does their effect on polarised light mean about optical isomers activity?

A

They are optically active.

23
Q

What happens when optical isomers are mixed in equal amounts?

A

Become optically inactive.

24
Q

Why do optical isomers become optically inactive when mixed in an equal amount?

A

The rotational effect of the plane-polarised light cancels out.

25
Q

What is the mixture of optical isomers mixed together evenly called?

A

A racemix mixture.