atom
gb/ˈætəm/ us/ˈætəm/
B1
English
~ 2500
Senses
0 senses
Noun
technical
B1
entity
1
smallest unit of an element
The tiniest part of an element that still has the same properties as that element.
Usage pattern:
an atom of [element]
Common mistake:
Learners sometimes confuse 'atom' with 'molecule'. An atom is a single particle of an element; a molecule is two or more atoms joined together.
Synonyms
particle (A more general term for a small piece of matter, not necessarily a chemical element.)
Antonyms
molecule (A molecule is made of two or more atoms bonded together, so it is larger and more complex.)
Collocations
split an atom
|hydrogen atom
|carbon atom
|atomic structure
|atom model
Themes
science
|chemistry
|physics
Examples
- A water molecule is made up of two hydrogen atoms and one oxygen atom.
- Scientists can split an atom to release energy.
- Every atom of gold has the same number of protons.
Learner examples
- An atom is very small.
- This is an atom of oxygen.
- Atoms make up all things.
Noun
B2
quantity
2
a very tiny amount
A very, very small amount of something.
Usage pattern:
not an atom of [something]
Common mistake:
Learners may overuse this figuratively; it is more common in formal or literary contexts than in casual speech.
Synonyms
bit (A small amount, but less emphatic than 'atom'.)
Antonyms
lot (A large amount, opposite in quantity.)
Collocations
not an atom of truth
|without an atom of doubt
Themes
measurement
|figurative
|core_vocabulary
Examples
- There isn’t an atom of truth in his story.
- She didn’t have an atom of doubt about his honesty.
- He showed not an atom of fear.
Learner examples
- There is not an atom of sugar in this tea.
- He has not an atom of doubt.
- She does not have an atom of fear.
Grammar
Dictionary form
atom
IPA
GB/ˈætəm/
US/ˈætəm/
Syllables & stress
atom (1 syllable)
Stress on 1st syllable (atom)
Word forms
Noun
- Base: atom
- Plural: atoms
Word family
Forms
atoms
noun
Core family
atomic
adjective B2
Related words
atomize
verb
atomization
noun
Advanced or less common
subatomic
adjective
atomically
adverb
Expressions
not an atom of truth
1/nˈɑt ən ˈætəm əv tɹˈuθ/
fixed phrase
no truth at all
It means that something is completely false.
Examples
- There is not an atom of truth in those rumors.
- His statement contained not an atom of truth.
split the atom
1/splˈɪt ðə ˈætəm/
fixed phrase
technical
break apart an atomic nucleus
To break the center of an atom to release energy.
Examples
- Nuclear power plants do not literally split the atom in the same way as early experiments did.
- The discovery that you could split the atom changed history.