chirality
chirality — adjective
- chiralitypositive
- more chiralitycomparative
- most chiralitysuperlative
1. describes an individual molecule or object whose mirror-image counterpart cannot
describes an individual molecule or object whose mirror-image counterpart cannot be aligned with the original by any rotation — the geometric property of handedness, illustrated by a left hand and a right hand that are mirror images but cannot occupy the same glove.
A chiral molecule, like the compound limonene, has left-handed and right-handed forms that smell completely different.
chiral + molecule; attributive use before noun
Niran checked whether the crystal was chiral by comparing it with its mirror image under the microscope.
predicative: is / was chiral
A person's left and right hands are chiral because one glove cannot fit both hands equally well.
When Eitan synthesised the chiral compound limonene in the lab, both mirror versions appeared together in the final mixture.
- non-superimposable
more literal and technical; describes the specific geometric relationship rather than a general class property
- enantiomorphic
rare; used mainly in crystallography to describe mirror-image crystal forms
- achiral
describes a molecule whose mirror image CAN be placed exactly on top of the original (e.g. methane, water)
文法句型
chiral + noun (molecule / compound / object / structure)
is / are chiral
用法筆記
Commonly used attributively before nouns like 'molecule', 'compound', 'substance', or 'catalyst'. The term comes from the Greek word for 'hand' — the hand is the classic example of a chiral object whose mirror image (the opposite hand) does not match the original.
常見錯誤
2. identifying a chemical substance or system as belonging to the class of compound
identifying a chemical substance or system as belonging to the class of compounds that exist as two distinct mirror-image forms, used when discussing their classification, recognition, or separation rather than the geometric relationship itself.
Glucose and other sugars are naturally chiral, and each mirror version rotates plane-polarised light in a different direction.
predicative use: be + chiral
The chiral nature of DNA determines how the molecule twists and fits inside the cell nucleus.
attributive: chiral + nature
Rohan studied the chiral environment inside the enzyme to understand why only the left-handed form of the drug was produced.
Pharmaceutical companies must test each chiral version of a new drug separately for safety and effectiveness.
- optically active
a property-based synonym; chiral compounds rotate plane-polarised light, though not all chiral substances are optically active in all forms
文法句型
chiral + noun (nature / environment / interaction / separation / recognition)
be chiral in nature / form
用法筆記
This sense focuses on the classification of substances as belonging to the chiral class — it is the most general of the three senses. Unlike sense 1, which emphasises the structural relationship to a mirror image, this sense simply identifies substances or phenomena that have the property of chirality.
常見錯誤
3. describing a specific atom within a molecule — most often a carbon atom — that h
describing a specific atom within a molecule — most often a carbon atom — that has four different atoms or groups attached to it, making the whole molecule capable of existing as mirror-image forms.
In alanine, the central carbon atom is called a chiral center because it bonds to four different groups.
attributive: chiral + center (most common collocation)
Soraya found three chiral carbon atoms in the plant compound by examining its structure with X-ray analysis.
attributive: chiral + carbon
The chiral carbon in lactic acid determines whether the solution rotates polarised light left or right.
Removing the hydroxyl group from the chiral center of lactic acid destroys its ability to exist as two mirror-image forms.
Bao mapped all the chiral centers in the protein to understand how the molecule folds inside the cell.
- asymmetric center
the preferred term in many textbooks; 'asymmetric' is broader but in this context refers specifically to a tetrahedral atom with four different substituents
- stereocenter
broader term that includes but is not limited to chiral centers; any atom where swapping two groups gives a different stereoisomer
文法句型
chiral + noun (center / carbon / atom / molecule)
用法筆記
This sense is narrower than senses 1 and 2: it refers specifically to an atom (the source of chirality) rather than the whole molecule. The most common collocations are 'chiral center' and 'chiral carbon.' A molecule may have one, several, or no chiral centers. Frequently used in stereochemistry and pharmaceutical research writing.