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Longman Dictionary of Contemporary English
a chain of atoms/molecules etctechnical:
▪ Most fabrics are made of long chains of molecules.
an atom/atomic bomb
▪ Oppenheimer was the father of the atomic bomb.
▪ In other cases atoms take the place of ions in regular lattice positions.
▪ Most other atoms can join up comfortably only with one, two, or three others at a time.
▪ In crystallography, each lattice point can accommodate more than a single atom.
▪ And the amount the tip is moved reveals the height of the protuberance, even if it is only a single atom high.
▪ The detection of single atoms in this way has caused great excitement because of its application in many areas.
▪ By the time it hits a distant screen, this ion-image has expanded millions of times. Single atoms can be resolved.
▪ In other words, only certain discrete energies would be permitted, exactly as for an electron confined in a single atom.
▪ Dalton never saw an atom, or the effects of a single atom.
▪ A single atom of copper is still a piece of copper.
▪ It is formed when the sun's ultraviolet radiation breaks up the two atoms of oxygen molecules into single atoms.
▪ We could detonate a very small atom bomb in the vicinity of another.
▪ Even a charge of conventional explosive in the vicinity of a small atom bomb would suffice.
▪ If the small atom bomb went up, so then would the hydrogen bomb.
▪ However, on the small scales of atoms and molecules, electromagnetic forces dominate.
▪ Pretty small for an atom bomb, I would have thought. 4000 kilotons.
▪ When small atoms bond together through ionic or covalent chemical bonds, the compactness of the bond makes it extremely strong.
▪ Carbon is the smallest atom in the fourth column of the periodic table of elements.
▪ We could detonate a very small atom bomb in the vicinity of another.
▪ A fart is not an atom bomb....
▪ Even a charge of conventional explosive in the vicinity of a small atom bomb would suffice.
▪ If the small atom bomb went up, so then would the hydrogen bomb.
▪ Teller, of course, worked on the atom bomb and the H-bomb.
▪ Britain has already accumulated enough nuclear waste to build 5,000 atom bombs.
▪ Then war intervened, Oppenheimer became involved in the atom bomb project, and he lost interest in gravitational collapse.
▪ Buckyballs, of buckminsterfullerene, are soccer-ball-shaped assemblages of 60 carbon atoms.
▪ Any molecule with this group attached to a carbon atom is called an alcohol.
▪ The two substances differ from each other only in the geometric pattern with which the carbon atoms are packed.
▪ In this group of ions the carbon atom is surrounded by three oxygen atoms in a planar triangle.
▪ In diamonds, the carbon atoms are packed in a tetrahedral pattern which is extremely stable.
▪ The hydrogen-to-#carbon atom ratio is perhaps a better index.
▪ This leaves one electron on each carbon atom unaccounted for.
▪ This is illustrated in Figure 4. 2 which shows the hydrogen-to-#carbon atom ratio of various hydrocarbon.
▪ By supplying addition molecules of chlorine it is possible to replace all the hydrogen atoms.
▪ The optimum proportions of hydrogen and oxygen are thus two hydrogen atoms per oxygen atom, exactly the same as in water.
▪ This is about the energy that would be released if a hydrogen atom could be totally converted into energy.
▪ A methyl group is a carbon with three hydrogen atoms attached.
▪ One of the hydrogen atoms in ammonia is replaced by a benzene ring.
▪ Instantly, one of the hydrogen atoms on the ethanol molecule is ripped off.
▪ It consists of a chain of carbon atoms, with one hydrogen atom attached to each carbon.
▪ The microcosm becomes the macrocosm: the key to the whole universe may well be hidden in one hydrogen atom.
▪ Thus, in our example, no magnesium, carbon or oxygen atoms can be created or destroyed.
▪ In this group of ions the carbon atom is surrounded by three oxygen atoms in a planar triangle.
▪ The clays consist of silica tetrahedra and the octahedra contain magnesia surrounded by oxygen atoms and hydroxyl groups.
▪ Is there a molecule that weighs the same as an oxygen atom?
▪ That instrument was designed to produce a beam of electrically charged atoms from the sample to be studied.
▪ The electrical charge used by neurons is carried by ions-those electrically charged atoms mentioned previously.
▪ For example, one molecule of oxygen contains two atoms of oxygen.
▪ One molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen.
▪ Each contains five atoms, giving nine normal vibrations.
▪ Nor would these, together with electrons, form separate, well-defined atoms.
▪ Quarks unite to form protons, neutrons and electrons, which in turn unite to form atoms.
▪ The sub-atomic particles are arranged to form the atoms, and different numbers, types and arrangements of atoms form the molecules.
▪ If the recoiled atom is directed towards a neighbouring atom, a blocking cone is formed behind the neighbouring atom.
▪ Negative ions can also be formed when an atom has an extra electron bolted on.
▪ Then J.J. Thomson showed that these atoms of charge exist; we call them electrons.
▪ They are named after the man who inferred their existence from weak attractive forces shown by atoms and molecules in gases.
▪ A formula of an ion shows the ratio of atoms of each element present in the ion.
▪ an atom of truth
▪ In graphite the carbon atoms are arranged in flat hexagons layered on top of each other.
▪ Quarks unite to form protons, neutrons and electrons, which in turn unite to form atoms.
▪ Talk of probability waves and eigen values does not undermine the reality of atoms and molecules.
▪ The formula also shows the number of moles of atoms of each element in one mole of molecules.
▪ The valency of an atom in a covalent molecule is the number of electrons shared by the atom in forming the bond.
The Collaborative International Dictionary

Atom \At"om\, n. [L. atomus, Gr. ?, uncut, indivisible; 'a priv. + ?, verbal adj. of ? to cut: cf. F. atome. See Tome.]

  1. (Physics)

    1. An ultimate indivisible particle of matter.

    2. An ultimate particle of matter not necessarily indivisible; a molecule.

    3. A constituent particle of matter, or a molecule supposed to be made up of subordinate particles.

      Note: These three definitions correspond to different views of the nature of the ultimate particles of matter. In the case of the last two, the particles are more correctly called molecules.

  2. (Chem.) The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule.

  3. Anything extremely small; a particle; a whit.

    There was not an atom of water.
    --Sir J. Ross.


Atom \At"om\, v. t. To reduce to atoms. [Obs.]

Douglas Harper's Etymology Dictionary

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; compare atomic.


n. 1 (context now historical English) The smallest medieval unit of time, equal to fifteen ninety-fourths of a second. (from 10th c.) 2 (context history of science English) A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter. (from 15th c.) 3 (context physics chemistry English) 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.)

  1. n. (physics and chemistry) the smallest component of an element having the chemical properties of the element

  2. (nontechnical usage) a tiny piece of anything [syn: molecule, particle, corpuscle, mote, speck]


An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are very small; typical sizes are around 100 pm (a ten-billionth of a meter, in the short scale). However, atoms do not have well-defined boundaries, and there are different ways to define their size that give different but close values.

Atoms are small enough that attempting to predict their behavior using classical physics - as if they were billiard balls, for example - gives noticeably incorrect predictions due to quantum effects. Through the development of physics, atomic models have incorporated quantum principles to better explain and predict the behavior.

Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and typically a similar number of neutrons. Protons and neutrons are called nucleons. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, that atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively, and it is called an ion.

The electrons of an atom are attracted to the protons in an atomic nucleus by this electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by a different force, the nuclear force, which is usually stronger than the electromagnetic force repelling the positively charged protons from one another. Under certain circumstances the repelling electromagnetic force becomes stronger than the nuclear force, and nucleons can be ejected from the nucleus, leaving behind a different element: nuclear decay resulting in nuclear transmutation.

The number of protons in the nucleus defines to what chemical element the atom belongs: for example, all copper atoms contain 29 protons. The number of neutrons defines the isotope of the element. The number of electrons influences the magnetic properties of an atom. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature, and is the subject of the discipline of chemistry.

Atom (disambiguation)

An atom is a basic unit of matter consisting of a nucleus within a cloud of one or more electrons.

Atom may also refer to:

Atom (order theory)

In the mathematical field of order theory, an element a of a partially ordered set with least element0 is an atom if 0 < a and there is no x such that 0 < x < a.

Equivalently, one may define an atom to be an element that is minimal among the non-zero elements, or alternatively an element that covers the least element 0.

Atom (measure theory)

In mathematics, more precisely in measure theory, an atom is a measurable set which has positive measure and contains no set of smaller but positive measure. A measure which has no atoms is called non-atomic or atomless.

Atom (Ray Palmer)

The Atom is a fictional superhero appearing in comic books published by DC Comics. The Atom was created by editor and co-plotter Julius Schwartz, writer Gardner Fox and penciler Gil Kane. He was one of the first superheroes of the Silver Age of comic books and debuted in Showcase #34 (Oct. 1961).

Atom (comics)

The Atom is a name shared by several fictional comic book superheroes from the DC Comics universe.

The original Golden Age Atom, Al Pratt, was created by Ben Flinton and Bill O'Connor and first appeared in All-American Publications' All-American Comics #19 (Oct. 1940). The second Atom was the Silver Age Atom, Ray Palmer, who first appeared in 1961. The third Atom, Adam Cray, was a minor character present in Suicide Squad stories. The fourth Atom, Ryan Choi, debuted in a new Atom series in August 2006. Another Atom from the 853rd Century first appeared as part of Justice Legion Alpha in August 1999.

The Atom has been the star of multiple solo series, and four of the five have appeared as members of various superhero teams, such as the Justice Society of America, the Justice League, the Suicide Squad, and the Justice Legion Alpha.

Atom (standard)

The name Atom applies to a pair of related Web standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.

Web feeds allow software programs to check for updates published on a website. To provide a web feed, the site owner may use specialized software (such as a content management system) that publishes a list (or "feed") of recent articles or content in a standardized, machine-readable format. The feed can then be downloaded by programs that use it, like websites that syndicate content from the feed, or by feed reader programs that allow Internet users to subscribe to feeds and view their content.

A feed contains entries, which may be headlines, full-text articles, excerpts, summaries, and/or links to content on a website, along with various metadata.

The Atom format was developed as an alternative to RSS. Ben Trott, an advocate of the new format that became Atom, believed that RSS had limitations and flaws—such as lack of on-going innovation and its necessity to remain backward compatible— and that there were advantages to a fresh design.

Proponents of the new format formed the IETF Atom Publishing Format and Protocol Workgroup. The Atom syndication format was published as an IETF proposed standard in RFC 4287 (December 2005), and the Atom Publishing Protocol was published as RFC 5023 (October 2007).

Atom (Al Pratt)

Al Pratt is a character in the DC Comics Universe, the original hero to fight crime as the Atom. He initially had no superpowers; instead, he was a diminutive college student and later a physicist, usually depicted as a "tough-guy" character.

Atom (video game)

Atom is a home computer game published by Tandy in 1983 for the TRS-80. The game educates the player about the first few elements of the periodic table ( Hydrogen through Xenon).

Atom (time)

“Atom” means in Greek “indivisible” and the word was (and still is) used to refer to anything that can be treated as a single indivisible unit: an “individual” (person) or a indivisible unit of matter (as in the particle atom in physics) or, in this case, as the smallest possible, i.e. indivisible, unit of time. One of the earliest occurrences of the word “atom” with the meaning of the smallest unit possible of measuring time (therefore ‘indivisible’) is found in the Greek text of the New Testament, in the 1st epistle of Paul to the Corinthians, chapter 15 verse 52 which gives the length of time of the “atom” too: the time needed for “the twinkling of an eye.” The text reads: “en atomo, en repe ophthamou” – the word "atom" is usually translated "a moment" - “In a moment, in the twinkling of an eye” (1Cor.15:52 KJV)- At least since then an atom of time was considered the smallest unit of time and with that meaning it was later referred to in medieval philosophical writings: as the smallest possible division of time. The earliest known occurrence in English is in Byrhtferth's Enchiridion (a science text) of 1010–1012, where it was defined as 1/564 of a momentum (1½ minutes), and thus equal to 15/94 of a second. It was used in the computus, the calculation used to determine the calendar date of Easter.

Atom (programming language)

Atom is a domain-specific language (DSL) in Haskell, for designing real-time embedded software.

Atom (Ryan Choi)

Ryan Choi is the fourth Atom that appears in DC Comics.

Atom (system on chip)

Atom is a system on chip (SoC) platform designed for smartphones and tablet computers, launched by Intel in 2012. It is a continuation of the partnership announced by Intel and Google on 13 September 2011 to provide support for the Android operating system on Intel x86 processors. This range competes with existing SoCs developed for the smartphone and tablet market from companies like Texas Instruments, Nvidia, Qualcomm and Samsung. Unlike these companies, which use ARM-based CPUs designed from the beginning to consume very low power, Intel has adapted the x86 based Atom line CPU developed for low power usage in netbooks, to even lower power usage.

Since April 2012, several manufacturers have released Intel Atom-based tablets and phones as well as using the SoCs as a basis for other small form factor devices (e.g. mini PCs, stick PCs, etc.).

In April 2016, Intel announced a major restructuring, including the cancellation of the SoFIA platform. It was reported by many news agencies that Broxton was cancelled.

Atom (text editor)

Atom is a free and open-source text and source code editor for OS X, Linux, and Windows with support for plug-ins written in Node.js, and embedded Git Control, developed by GitHub. Atom is a desktop application built using web technologies. Most of the extending packages have free software licenses and are community-built and maintained. Atom is based on Electron (formerly known as Atom Shell), a framework that enables cross-platform desktop applications using Chromium and Node.js. It is written in CoffeeScript and Less. It can also be used as an IDE. Atom was released from beta, as version 1.0, on June 25, 2015. Its developers call it a "hackable text editor for the 21st Century".


The ATOM is a heavy 8×8 infantry fighting vehicle (IFV) jointly developed by the Russian company Petrel (a division of Uralvagonzavod) and the French company Renault Trucks. The vehicle is established on the basis of the French Véhicule blindé de combat d'infanterie (VBCI) IFV which is produced by Renault. The prototype of the ATOM was first unveiled during the 2013 Russian Arms Expo at Nizhny Tagil, equipped with a unique fighting module.

On 8 April 2014, Volvo (the parent company of Renault Trucks) froze the joint project of Renault Trucks with Uralvagonzavod. Renault Trucks required consent from the Swedish government to do install the engines for the vehicle and were declined because of "uncertainty" according to the Swedish side. The project of cooperation with Uralvagonzavod was influenced by the recent political situation in Crimea. On 18 June 2014, a spokesman for Renault Trucks told IHS Jane's, that the program remains frozen despite contradicting claims given by Rosoboronexport deputy director general Igor Sevastianov.

After the withdrawal of Renault, UVZ continued to the project alone. It is planned to make an appearance at the Russian Arms Expo in September 2015.

Usage examples of "atom".

Epicurus, atoms be the cause of all things and that life be nothing else but an accidentary confusion of things, and death nothing else, but a mere dispersion and so of all other things: what doest thou trouble thyself for?

Then I suffered a vision of Acer Laidlaw piloting Eightball back to Roderick Station with a hold full of atoms that had once been mine, and gritted my teeth so hard I cracked a filling.

But when the atoms come under the influence of the higher-level morphogenetic field of a molecule, these probabilities are modified in such a way that the probability of events leading toward the actualization of the final form are enhanced, while the probability of other events is diminished.

I placed one of these leaves under the microscope, and saw innumerable atoms of lime adhering to the external surface of the secretion.

The formula of one steroid produced by the adrenal cortex is presented schematically on page 78, with each of the 21 carbon atoms marked off by number.

The tidal regularity of cerebral chemical flows, the cyclonic violence latent in the adrenergic current of the autonomic nervous system, the delicate mysteries of the sweep of oxygen atoms from pneumonic membrane into the bloodstream.

The resulting atom combination, -CHO, is called an aldehyde group, for reasons we need not go into.

The Annihilator translates the strong nuclear force into electromagnetism for a fraction of a second, causing atoms to instantly fling apart.

He developed the pleasure ethic of Aristippus and combined it with the atom theory of Democritus.

The particles of which they were made were born, in the great clumsy bevatrons of that age, some micro-seconds in the future, and their assembly into atoms of anti-matter in the present time of the observers was in fact the moment of their death.

Rather than devise a model of the atom based on theoretical ideas as Thomson had done, Rutherford intended to probe atomic structure by bombarding atoms with particles ejected from radioactive atoms.

Like cerements at a played-out masque, the rough And reptile skins of us whereon we set The stigma of scared years -- are we to get Where atoms and the ages are one stuff.

The chloroplasts of a plant cell-small green particles containing chlorophyll-absorb the energy of sunlight to split water molecules into hydrogen and oxygen atoms.

In the starpatterns he saw the origin: light, the ardor and selflessness of It, the chthonic journey, descanting into geometry, echoing across the shell of time as language: mesons talking atoms into being, molecular communities communicating, no end to It, only addition, time, the futureless deception, until the final addition, the mindfire of consciousness that burns through the drug of dreams and anneals the pain of living with the living pain.

Its rotundity was first lost, it assumed the semblance of a featureless disk of pallid light, which swiftly widened till it obscured all else, then seemed to advance upon and envelope her bodily, so that she became spiritually a part of it, an atom of identity engulfed in a limpid world of glareless light, light that had had no rays and issued from no source but was circumambient and universal.