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The Collaborative International Dictionary
Atomic weight

Atomic \A*tom"ic\, Atomical \A*tom"ic*al\, a. [Cf. F. atomique.]

  1. Of or pertaining to atoms.

  2. Extremely minute; tiny.

    Atomic bomb, see atom bomb in the vocabulary.

    Atomic philosophy, or Doctrine of atoms, a system which, assuming that atoms are endued with gravity and motion, accounted thus for the origin and formation of all things. This philosophy was first broached by Leucippus, was developed by Democritus, and afterward improved by Epicurus, and hence is sometimes denominated the Epicurean philosophy.

    Atomic theory, or the Doctrine of definite proportions (Chem.), teaches that chemical combinations take place between the supposed ultimate particles or atoms of bodies, in some simple ratio, as of one to one, two to three, or some other, always expressible in whole numbers.

    Atomic weight (Chem.), the weight of the atom of an element as compared with the weight of the atom of hydrogen, taken as a standard.

Atomic weight

Weight \Weight\, n. [OE. weght, wight, AS. gewiht; akin to D. gewigt, G. gewicht, Icel. v[ae]tt, Sw. vigt, Dan. v[ae]gt. See Weigh, v. t.]

  1. The quality of being heavy; that property of bodies by which they tend toward the center of the earth; the effect of gravitative force, especially when expressed in certain units or standards, as pounds, grams, etc.

    Note: Weight differs from gravity in being the effect of gravity, or the downward pressure of a body under the influence of gravity; hence, it constitutes a measure of the force of gravity, and being the resultant of all the forces exerted by gravity upon the different particles of the body, it is proportional to the quantity of matter in the body.

  2. The quantity of heaviness; comparative tendency to the center of the earth; the quantity of matter as estimated by the balance, or expressed numerically with reference to some standard unit; as, a mass of stone having the weight of five hundred pounds.

    For sorrow, like a heavy-hanging bell, Once set on ringing, with his own weight goes.

  3. Hence, pressure; burden; as, the weight of care or business. ``The weight of this said time.''

    For the public all this weight he bears.

    [He] who singly bore the world's sad weight.

  4. Importance; power; influence; efficacy; consequence; moment; impressiveness; as, a consideration of vast weight.

    In such a point of weight, so near mine honor.

  5. A scale, or graduated standard, of heaviness; a mode of estimating weight; as, avoirdupois weight; troy weight; apothecaries' weight.

  6. A ponderous mass; something heavy; as, a clock weight; a paper weight.

    A man leapeth better with weights in his hands.

  7. A definite mass of iron, lead, brass, or other metal, to be used for ascertaining the weight of other bodies; as, an ounce weight.

  8. (Mech.) The resistance against which a machine acts, as opposed to the power which moves it. [Obs.]

    Atomic weight. (Chem.) See under Atomic, and cf. Element.

    Dead weight, Feather weight, Heavy weight, Light weight, etc. See under Dead, Feather, etc.

    Weight of observation (Astron. & Physics), a number expressing the most probable relative value of each observation in determining the result of a series of observations of the same kind.

    Syn: Ponderousness; gravity; heaviness; pressure; burden; load; importance; power; influence; efficacy; consequence; moment; impressiveness.

atomic weight

n. 1 former term for the more specific relative atomic mass. 2 A term used to represent the mean relative atomic mass of an element in nature, as distinct from the relative atomic mass of a single isotope.

atomic weight

n. (chemistry) the ratio of the atomic mass of an element to half the atomic mass of carbon-12 [syn: relative atomic mass]

Usage examples of "atomic weight".

The number of positively charged particles is what they call the 'atomic number,' and these particles, together with the uncharged particles, make up the 'atomic weight.

In atoms lighter than atomic weight 50 it will not maintain itself, for their energy is consumed.

Since an atom is electrically neutral overall, the number of electrons must equal the number of protons, and it is this 'atomic number', not the atomic weight, that organizes the periodicities found by Mendeleev However, the atomic weight is usually about twice the atomic number, because the number of neutrons in an atom is pretty close to the number of protons for quantum reasons, so you get much the same ordering whichever quantity you use.

It has three times the atomic weight of hydrogen, because of the additional neutrons.

He'd explain the disintegration field, which collapses the electrons of hydrogen so that it rises in atomic weight to helium, and the helium to lithium, while the oxygen of the water is split literally into neutronium and pure force.

One cannot begin small, first extracting from uranium ores isotope with the atomic weight of 235, then setting off a chain reaction, above critical mass, synthesizing plutonium, and thus obtaining a detonator for hydrogen-tritium bombs.

We know that the naturally radioactive elements are all in the group of those with the highest atomic weight.

This body, the radium, gives a characteristic spectrum, and I was able to determine for it an atomic weight much higher than that of the barium.

The mysterious substitution of a strange element for tungsten or osmium in various laboratories, the tests indicating that its atomic number was that of plutonium but its atomic weight was far too low, the absurd but necessary theory that the stuff was a gift from some parallel universe and--finally--the fact that the new element, stable when it first arrived, rapidly began to undergo radioactive decay in a startlingly accelerative way.

Eventually Beatryx would be made to understand that four hydrogen atoms had a combined atomic weight of 4.