Atom meaning

ăt'əm
The definition of an atom is the smallest component of an element, characterized by a sharing of the chemical properties of the element and a nucleus with neutrons, protons and electrons.
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The protons and the neutrons reside in the nucleus.
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(now historical) The smallest medieval unit of time, equal to fifteen ninety-fourths of a second. [from 10th c.]
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(history of science) A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter. [from 15th c.]
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Any of the indivisible particles postulated by philosophers as the basic component of all matter.
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The smallest unit of an element, consisting of at least one proton and (for all elements except hydrogen) one or more neutrons in a dense central nucleus, surrounded by one or more shells of electrons. In electrically neutral atoms, the number of protons equals the number of electrons. Atoms remain intact in chemical reactions except for the removal, transfer, or exchange of certain electrons.
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(1) (Atom) Intel x86 chips. See Intel Atom.
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(physics, chemistry) The smallest possible amount of matter which still retains its identity as a chemical element, now known to consist of a nucleus surrounded by electrons. [from 16th c.]

A molecule is a close combination of atoms.

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A mote of dust in a sunbeam. [from 16th c.]
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(computing, programming, Lisp) An individual number or symbol, as opposed to a list. A scalar value.
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An extremely small part, quantity, or amount.
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A very small amount (of something immaterial); a whit. [from 17th c.]
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(mathematics) A non-zero member of a Boolean algebra that is not a union of any other elements. [from 20th c.]
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An atom includes a nucleus, and then a series of orbital circles that surround this nucleus similar to the solar system structure.
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The electrons are in the orbitals.
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The amount of protons in the nucleus of an atom determines its atomic number.

Hydrogen and helium are examples of elements that have an atom.

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A tiny particle of anything; jot.
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Any of the smallest particles of an element that combine with similar particles of other elements to produce compounds: atoms combine to form molecules, and consist of a complex arrangement of electrons revolving about a positively charged nucleus containing (except for hydrogen) protons and neutrons and other particles.
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The smallest, indivisible constituent part or unit of something. (Now generally interpreted as a figurative use of the physics sense, above.) [from 17th c.]
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the atom
  • Nuclear energy.
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Idioms and Phrasal Verbs

the atom

Origin of atom

  • Middle English attome from Latin atomus from Greek atomos indivisible, atom a- not a–1 tomos cutting (from temnein to cut tem- in Indo-European roots)
    From American Heritage Dictionary of the English Language, 5th Edition
  • From Middle French atome, from Latin atomus (“smallest particle”), from Ancient Greek ἄτομος (atomos, “indivisible”), from ἀ- (a-, “not”) + τέμνω (temnō, “I cut”).
    From Wiktionary

Atom Sentence Examples

  • An atom is made up of protons, neutrons, and electrons.

  • When an atom is charged, it becomes an ion.

  • There's not an atom of dirt in her house because she never stops cleaning.

  • A molecule may be defined as the smallest part of a substance which can exist alone; an atom as the smallest part of a substance which can exist in combination.

  • Dalton believed that the molecules of the elementary gases consisted each of one atom; his diagram for hydrogen gas makes the point clear.

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Words near atom in the Dictionary