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Meaning & use

molecule

noun·Academicchemistry

Last updated

UK/ˈmɒlɪkjuːl/
US/ˈmɑːlɪkjuːl/

Meanings

  1. nouncountablechemistry

    The smallest unit of a substance that still has its chemical properties, made of two or more bonded atoms.

    Grammar: Has plural molecules; a single atom is usually not called a molecule except in special monatomic cases.

    Patterns

    • water molecule
    • molecule of DNA
    • a molecule consists of atoms

    A water molecule contains two hydrogen atoms and one oxygen atom.

    The model showed how a methane molecule is arranged in space.

    Heating the liquid gave the molecules enough energy to escape as gas.

  2. nounsingularfigurative

    An extremely small amount, used mainly in negative statements for emphasis.

    Grammar: Almost always appears as not a molecule of plus an abstract noun.

    Patterns

    • not a molecule of truth
    • not a molecule of evidence

    There is not a molecule of evidence linking him to the missing file.

    Her apology contained not a molecule of sincerity.

    The rumor has not a molecule of truth behind it.

Word forms

pluralmolecules

Common combinations

water molecule
Each water molecule has a bent shape.
molecule of DNA
The dye can attach to a molecule of DNA under UV light.
split a molecule
The catalyst helps split the molecule without adding heat.
not a molecule of evidence
The defense argued there was not a molecule of evidence for the claim.

Synonyms and how they differ

particle
Particle is broader and can refer to dust, physics units, or grammar; molecule specifically means bonded atoms in chemistry.
atom
An atom is a single unit of an element; molecules are built from atoms bonded together.
compound
A compound is a substance made when elements chemically combine, while a molecule is one particle of such a substance.
unit
Unit is a general word for one measured part and lacks the chemical bonding meaning.

Word family

molecular adjective
Relating to molecules or the structure and behavior of molecules.

Commonly confused: molecule or atom?

molecule vs atom

An atom is one elemental unit; a molecule is two or more atoms joined by chemical bonds.

Practice

A water ___ is made of two hydrogen atoms and one oxygen atom.

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