Atom
AT-uhm
/ˈætəm/
The smallest unit of an ordinary matter that forms a chemical element, consisting of a nucleus (protons and neutrons) and electrons orbiting it.
Atoms are the fundamental building blocks of all matter and are defined by their number of protons, which determines the element.
The story behind the word. The word 'atom' comes from the Ancient Greek 'atomos,' meaning 'uncuttable' or 'indivisible.' This term was used by Greek philosophers like Democritus and Leucippus to describe the smallest, fundamental particles of matter that could not be further divided. Although modern physics has shown that atoms can be split, the name persists as a testament to this ancient philosophical concept.
Word relationships
- Particle: More general; can refer to any tiny piece of matter, not necessarily the fundamental unit of an element.
- Unit: More general; refers to a single distinct part of a larger whole.
Commonly confused with
- Molecule: An 'atom' is the smallest unit of an element; a 'molecule' is a group of two or more atoms chemically bonded together.
Word family
- atomic (adjective): Relating to an atom or atoms.
- atomize (verb): To reduce to atoms or fine particles.
Collocations
- hydrogen atom
- carbon atom
- single atom
- atomic structure
- splitting the atom
Idioms & expressions
- every atom of one's being
Example sentences
- "Even the air we breathe is composed of countless tiny atoms of nitrogen and oxygen." All matter is made of atoms.
- "The Rutherford model famously described the atom as having a dense nucleus with electrons orbiting it." The structure of an atom.
Memory hook
Remember 'atomos' means 'uncuttable' – think of an 'atom' as the smallest, fundamental piece you can't easily cut. Uncuttable piece
When not to use
Do not use 'atom' interchangeably with 'molecule'; a molecule is a collection of atoms, while an atom is the basic unit of an element.
Fun facts
- The idea of atoms dates back to ancient Greece, long before experimental evidence confirmed their existence.
- Despite their name, atoms are indeed divisible, as demonstrated by nuclear fission and fusion.
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