When a compound rotates plane polarized light, it is said to be optically active. There are two types of optical isomers: dextrorotatory isomers rotate polarized light to the right, while levorotatory isomers rotate it to the left. Optical isomers are non-superimposable mirror images of each other that contain a chiral or asymmetric carbon atom bonded to four different groups. A polarimeter is used to measure the optical activity of compounds.

1. Optical Activity
When a compound rotate the plane Polarized Light
than it is said to be optically active and this
phenomenon is called optical activity.
1. Dextrorotatory Isomer (+ compound): A
compound is said to be dextrorotatory when it
rotate plane Polarized Light on right side. Dextro
means right hand.
2. Levororatory Isomer (- compound): A compound
is said to be levorotatory when it rotate plane
Polarized Light on left side. Levo means left hand.
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2. Chirality Optical Activity in Glucose
**

3. Light that vibrates in one plane is
called as Plane Polarized Light
Light can be divided into two types according to
wavelength.
1. Polychromatic Light: Light that composed of
many wavelengths are called as
polychromatic light. All lights Gamma, X-rays,
UV, IR are polychromatic light.
2. Monochromatic Light: Light that composed
of a single wavelength is called as
monochromatic light. Monochromatic light
can be selected for studying of properties of
compounds. For example optical activity.
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4. Polarimeter
An instrument that is used for the measurement
of optical activity of a compound is called as
polarimeter
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5. Plane polarizer are mostly Nicol Prism made up of calcite (CaCO3)
Dextrorotatory
Levorotatory

6. 2. Optical Isomerism
Optical Isomers: Different compounds that are
mirror images of each other and non
superimposable are called as optical isomers.
These isomers are formed due to rotation of Plane
Polarized Light either clockwise Dextrorotatory or
anti clockwise Levororatory. These isomers have
chiral (asymmetric) carbon atom.
Chiral Carbon (Chiral centre)
Carbon that attaches with four different atoms
(groups) is called chiral (asymmetric)carbon.
Chiral means handedness
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8. Chiral Compounds are mirror images of each other
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9. Chiral means hand
like property. As
left hand is mirror
image of right
hand, similarly
Chiral molecules
are mirror images
of each other

10. Two types of Lactic Acids (
Dextrorotatory(d) Levorotatory(l)
Optical Isomers are also called as Enantiomers

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