Atom
AT-uhm
/ˈætəm/
The smallest unit of an element that retains the chemical identity of that element.
While once thought to be indivisible, atoms are now known to consist of subatomic particles (protons, neutrons, electrons), but they remain the fundamental unit in chemical reactions.
The story behind the word. The word 'atom' comes from the ancient Greek 'atomos,' meaning 'uncuttable' or 'indivisible.' This idea was championed by philosophers like Democritus, who believed that matter was made of tiny, fundamental particles that could not be broken down further. While modern science has shown atoms are indeed divisible into subatomic particles, the name stuck, honoring the foundational concept of these ultimate building blocks.
Word relationships
- particle: More general term for a tiny piece of matter; an atom is a specific type of particle.
- corpuscle: An older, less common term, sometimes used for a minute particle, especially in biology.
Commonly confused with
- Molecule: An atom is a single unit of an element; a molecule is a group of two or more atoms bonded together.
- Element: An element is a pure substance made up of only one type of atom; an atom is the smallest unit of that element.
Word family
- atomic (adjective): Relating to atoms; extremely small.
- atomize (verb): To reduce to atoms or fine particles; to destroy completely.
Collocations
- hydrogen atom
- carbon atom
- single atom
- atom bomb
Idioms & expressions
- not an atom of (doubt/truth)
Example sentences
- "Every atom of gold is identical, giving the metal its consistent properties." Describing the basic unit of matter.
- "The nucleus of an atom contains protons and neutrons, while electrons orbit around it." From a scientific explanation.
- "Ancient Greek philosophers, like Democritus, first proposed the concept of the atom as an indivisible particle." Discussing the history of science.
Memory hook
Think of an 'A-TOM' as the 'A-ll Time Original Matter' – the most basic, fundamental piece. A-TOM: All Time Original Matter
When not to use
Do not use 'atom' to refer to any tiny particle; it specifically refers to the smallest unit of a chemical element.
Fun facts
- If an atom were the size of a football stadium, its nucleus would be the size of a pea at the center.
- The vast majority of an atom's mass is concentrated in its tiny nucleus.
Also appears in
Take your vocabulary further with LangBlitz
Our English vocabulary app: FSRS spaced repetition, 5,000+ curated words across 119 topic groups, CEFR A1 to C2. Explore your mastery with the beautiful Vocabulary World feature.