atom

[at-uh m] /ˈæt əm/
noun
1.
Physics.
  1. the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element.
  2. an atom with one of the electrons replaced by some other particle:
    muonic atom; kaonic atom.
2.
Energy. this component as the source of nuclear energy.
3.
a hypothetical particle of matter so minute as to admit of no division.
4.
anything extremely small; a minute quantity.
Origin
1350-1400; Middle English attomos, athomus < Latin atomus < Greek átomos, noun use of átomos undivided, equivalent to a- a-6 + tomós divided, verbid of témnein to cut
Synonyms
4. shred, speck, scintilla, iota, jot, whit.
Examples from the web for atoms
  • These atoms are missing an electron and are thus positively charged.
  • Ozone is a highly reactive molecule that contains three oxygen atoms.
  • The atomic transistor works, as its name suggests, by shuffling individual atoms around within the device.
  • Cool a gas of rubidium atoms to one-hundred-millionth of a degree above absolute zero or less and something strange happens.
  • The two new elements are radioactive and only exist for less than a second before decaying into lighter atoms.
  • When a neutron hits metal, it displaces atoms within the crystal lattice.
  • Hydrogen atoms are the smallest and lightest in the universe.
  • The best approximation of the number of atoms in a kilo of mixed-isotope silicon is still an order of magnitude too vague.
  • The conductor's atoms impede the flow, causing power to dissipate as heat.
  • In doing that calculation, it helps a lot if you know what the atoms in question are-in other words, the amino-acid sequence.
British Dictionary definitions for atoms

atom

/ˈætəm/
noun
1.
  1. the smallest quantity of an element that can take part in a chemical reaction
  2. this entity as a source of nuclear energy: the power of the atom See also atomic structure
2.
any entity regarded as the indivisible building block of a theory
3.
the hypothetical indivisible particle of matter postulated by certain ancient philosophers as the fundamental constituent of matter See also atomism
4.
a very small amount or quantity; minute fragment: to smash something to atoms, there is not an atom of truth in his allegations
Word Origin
C16: via Old French and Latin, from Greek atomos (n), from atomos (adj) that cannot be divided, from a-1 + temnein to cut
Word Origin and History for atoms

atom

n.

late 15c., as a hypothetical indivisible body, the building block of the universe, from Latin atomus (especially in Lucretius) "indivisible particle," from Greek atomos "uncut, unhewn; indivisible," from a- "not" + tomos "a cutting," from temnein "to cut" (see tome). An ancient term of philosophical speculation (in Leucippus, Democritus), revived 1805 by British chemist John Dalton. In late classical and medieval use also a unit of time, 22,560 to the hour. Atom bomb is from 1945 as both a noun and a verb; cf. atomic.

atoms in Medicine

atom at·om (āt'əm)
n.

  1. A unit of matter, the smallest unit of an element, having all the characteristics of that element and consisting of a dense, central, positively charged nucleus surrounded by a system of electrons. The entire structure has an approximate diameter of 10-8 centimeter and characteristically remains undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons.

  2. This unit regarded as a source of nuclear energy.

  3. A part or particle considered to be an irreducible constituent of a specified system.

  4. The irreducible, indestructible material unit postulated by ancient atomism.

  5. An extremely small part, quantity, or amount.

a·tom'ic (ə-tŏm'ĭk) adj.
atoms in Science
atom
(āt'əm)
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. Compare compound. See also ion, isotope, orbital.

atoms in Culture

atom definition


A unit of matter; the smallest unit of a chemical element. Each atom consists of a nucleus, which has a positive charge, and a set of electrons that move around the nucleus. (See Bohr atom.)

Note: Atoms link together to form molecules.