atom
A-tuhm
Atom (noun) means the smallest unit of a chemical element that retains its properties, made up of a nucleus and surrounding electrons. Example: “Every atom of oxygen has eight protons.”
noun
1
The smallest unit of a chemical element that retains its properties, made up of a nucleus and surrounding electrons.
"Every atom of oxygen has eight protons."
"Splitting the atom released enormous amounts of energy."
"A water molecule contains two hydrogen atoms and one oxygen atom."
2
A tiny or minimal amount of something.
"There isn't an atom of truth in that rumor."
"He didn't show an atom of guilt about being late."
"There wasn't an atom of space left on the crowded train."
How to use atom
Learner’s notesIn plain EnglishThe basic building block of matter — or, informally, the tiniest possible amount of something.
Easily confused with
Common pairings
split the atom
an atom of truth
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Word forms
- Plural
- atoms
Fill the gap
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Every _____ of oxygen has eight protons.
Etymology
From Latin atomus, from Greek atomos ("indivisible"), from a- ("not") + temno ("to cut"). Ancient philosophers imagined atoms as the smallest possible pieces of matter, though we now know atoms themselves are divisible.
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Frequently asked questions
What does “atom” mean?
The word “atom” means the smallest unit of a chemical element that retains its properties, made up of a nucleus and surrounding electrons. In plain terms, the basic building block of matter — or, informally, the tiniest possible amount of something.
How do you pronounce “atom”?
“Atom” is pronounced A-tuhm ([ˈæɾm̩] in IPA).
How do you use “atom” in a sentence?
Here is “atom” used in a sentence: “Every atom of oxygen has eight protons.”
What part of speech is “atom”?
“Atom” is a noun.
Where does the word “atom” come from?
The word “atom” comes from Latin. From Latin atomus, from Greek atomos ("indivisible"), from a- ("not") + temno ("to cut"). Ancient philosophers imagined atoms as the smallest possible pieces of matter, though we now know atoms themselves are divisible.
Is “atom” a common word?
“Atom” is an uncommon word in modern English, usually learned at around the A2 level.
How many meanings does “atom” have?
“Atom” has 2 distinct senses listed in this dictionary. The most common is: the smallest unit of a chemical element that retains its properties, made up of a nucleus and surrounding electrons.
What is the difference between an atom and a molecule?
An atom is the smallest unit of a chemical element that retains its properties, made up of a nucleus and surrounding electrons, while a molecule forms when two or more atoms bond together. A molecule can therefore consist of atoms from one element or several different elements.
Can atom be used figuratively?
Yes, atom can be used figuratively to mean a tiny or minimal amount of something, as in 'not an atom of truth', extending its scientific sense of smallness to describe negligible quantities in general.
What is the difference between an atom and an electron?
An atom is a complete unit made up of a nucleus and surrounding electrons, while an electron is just one of the smaller particles that orbit within an atom. An electron is therefore a component part of an atom, not a separate whole unit.
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