Organic Chemistry 3.1 - Stereo Chemistry - Optical Isomers Flashcards
What are isomers?
compounds with the same molecular formula, but different structural formula
Isomers are compounds with the same ___ formula, but different ___ formula
molecular, structural
Name the different types of isomers please
- Structural isomers (higher)
- Stereoisomers (optical and geometric)
What are structural isomers?
compounds with the same atoms, but bonded together in a different order
(eg butane and 2-methylpropane)
What are stereoisomers?
Stereoisomers are compounds with bonding between atoms in exactly the same order, but a different spatial arrangement. (eg left hand right hand)
Stereoisomers are compounds with ___ between ___ in exactly the same order, but a different ___ ___.
bonding, atoms, spatial arrangement
What is an optical isomer?
when a molecule’s mirror image is non-superimposable
An optical isomer is when a molecule’s ___ image is…
mirror, non-superimposable
A molecule that is non-superimposable is said to be…
chiral. (distinguishable from it’s partner, asymmetrical)
Mirror images can be ___, or ___.
identical or different.
Optical isomers exist for compounds with…
four different atoms/groups arranged tetrahedrally around a carbon atom.
A pair of optical isomers are described as ___.
enantomers
A 50/50 mixture of two enantomers is called a…
racemic mixture
What are enantomers?
a pair of optical isomers (‘optically active molecules’)
What is a racemic mixture?
an even (50/50) mixture of two enantomers
When a carbon has four different groups attached, it is described as ___.
chiral
Normal light vibrates in ___ ___.
Plane-polarised light vibrates in ___ ___.
all directions.
one direction
How can plane-polarised light be produced?
passing light through a polarised filter
What affect do (a pair of) enantomers have on plane polarised light?
The two molecules rotate plane polarised light by the same degree, but in opposite directions
A substance is said to be optically active if…
it can rotate a plane of polarised light
Are racemic mixtures optically active?
Why?
no.
because the opposite rotations of a plane of light cancel each other out
In which two ways do enantomers act differently?
when rotating plane polarised light,
and when in a chiral environment (eg a biological system)
Chiral molecules react differently with other ___ ___.
chiral molecules
Enantomers have ___ chemical properties, except when in a ___ environment, such as a ___ system.
identical, chiral, biological
Different enantomers can have different effects on…
the body
Give an example of something with an identical mirror image, and something with a non superimposable mirror image.
A pencil
your hands
